HMH

SEC source: 0001193125-26-140142 · ownership.xml · derivative · entry 6

Baker Hughes Co · CIK 0001701605 · Director · 10% owner · Director by Deputization

Baker Hughes Holdings LLC · CIK 0000808362 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Baker Hughes Holdings LLC

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_price: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · kind: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.expiration_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · ownership.nature: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F3 · ownership.nature: Baker Hughes Company has an indirect pecuniary interest in the securities held by each of Baker Hughes Holdings LLC. Consequently, Baker Hughes Company may be deemed to share beneficial ownership in the securities held directly by Baker Hughes Holdings LLC. The board of directors and officers of Baker Hughes Company disclaim beneficial ownership with respect to such securities.

F4 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F5 · ownership.nature: Judson E. Bailey and M. Georgia Magno are directors of the Issuer and were nominated for such roles by Baker Hughes Holdings LLC. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Baker Hughes Holdings LLC may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0001193125-26-140142 · ownership.xml · derivative · entry 5

Baker Hughes Co · CIK 0001701605 · Director · 10% owner · Director by Deputization

Baker Hughes Holdings LLC · CIK 0000808362 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Baker Hughes Holdings LLC

Disclosed balance after: 0

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_price: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · kind: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.expiration_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · ownership.nature: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F3 · ownership.nature: Baker Hughes Company has an indirect pecuniary interest in the securities held by each of Baker Hughes Holdings LLC. Consequently, Baker Hughes Company may be deemed to share beneficial ownership in the securities held directly by Baker Hughes Holdings LLC. The board of directors and officers of Baker Hughes Company disclaim beneficial ownership with respect to such securities.

F4 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F5 · ownership.nature: Judson E. Bailey and M. Georgia Magno are directors of the Issuer and were nominated for such roles by Baker Hughes Holdings LLC. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Baker Hughes Holdings LLC may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0001193125-26-140142 · ownership.xml · derivative · entry 4

Baker Hughes Co · CIK 0001701605 · Director · 10% owner · Director by Deputization

Baker Hughes Holdings LLC · CIK 0000808362 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Baker Hughes Holdings LLC

Disclosed balance after: 0

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_price: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · kind: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.expiration_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · ownership.nature: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F3 · ownership.nature: Baker Hughes Company has an indirect pecuniary interest in the securities held by each of Baker Hughes Holdings LLC. Consequently, Baker Hughes Company may be deemed to share beneficial ownership in the securities held directly by Baker Hughes Holdings LLC. The board of directors and officers of Baker Hughes Company disclaim beneficial ownership with respect to such securities.

F4 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F5 · ownership.nature: Judson E. Bailey and M. Georgia Magno are directors of the Issuer and were nominated for such roles by Baker Hughes Holdings LLC. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Baker Hughes Holdings LLC may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0001193125-26-140142 · ownership.xml · derivative · entry 3

Baker Hughes Co · CIK 0001701605 · Director · 10% owner · Director by Deputization

Baker Hughes Holdings LLC · CIK 0000808362 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Baker Hughes Holdings LLC

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 1,050,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_price: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · kind: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.expiration_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · ownership.nature: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F3 · ownership.nature: Baker Hughes Company has an indirect pecuniary interest in the securities held by each of Baker Hughes Holdings LLC. Consequently, Baker Hughes Company may be deemed to share beneficial ownership in the securities held directly by Baker Hughes Holdings LLC. The board of directors and officers of Baker Hughes Company disclaim beneficial ownership with respect to such securities.

F4 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F5 · ownership.nature: Judson E. Bailey and M. Georgia Magno are directors of the Issuer and were nominated for such roles by Baker Hughes Holdings LLC. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Baker Hughes Holdings LLC may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0001193125-26-140142 · ownership.xml · derivative · entry 2

Baker Hughes Co · CIK 0001701605 · Director · 10% owner · Director by Deputization

Baker Hughes Holdings LLC · CIK 0000808362 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Baker Hughes Holdings LLC

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 1,050,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_price: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · kind: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.exercise_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · derivative.expiration_date: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · ownership.nature: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F3 · ownership.nature: Baker Hughes Company has an indirect pecuniary interest in the securities held by each of Baker Hughes Holdings LLC. Consequently, Baker Hughes Company may be deemed to share beneficial ownership in the securities held directly by Baker Hughes Holdings LLC. The board of directors and officers of Baker Hughes Company disclaim beneficial ownership with respect to such securities.

F4 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F5 · ownership.nature: Judson E. Bailey and M. Georgia Magno are directors of the Issuer and were nominated for such roles by Baker Hughes Holdings LLC. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Baker Hughes Holdings LLC may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0001193125-26-140142 · ownership.xml · nonDerivative · entry 1

Baker Hughes Co · CIK 0001701605 · Director · 10% owner · Director by Deputization

Baker Hughes Holdings LLC · CIK 0000808362 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Baker Hughes Holdings LLC See footnotes

Disclosed balance after: 16,288,748

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · kind: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F4 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), Baker Hughes Holdings LLC, a wholly owned subsidiary of Baker Hughes Company, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Baker Hughes Company and Baker Hughes Holdings LLC are collectively referred to as "Baker Hughes". In connection with the corporate reorganization and Baker Hughes' participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Baker Hughes Company held 17,338,748 B.V. Voting Class B Shares and 17,338,748 B.V. Voting Class A Shares (through Baker Hughes Holdings LLC);

F2 · ownership.nature: (Continued from footnote 1) second, HMH B.V. recapitalized to convert (i) Baker Hughes Holdings LLC's 16,288,748 B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) its 16,288,748 B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); third, (i) Baker Hughes Holdings LLC sold 1,050,000 B.V. Voting Class B Shares and 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) Baker Hughes Holdings LLC received 16,288,748 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on its remaining 16,288,748 B.V. Voting Class B Shares and 16,288,748 B.V. Voting Class A Shares that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares and 16,288,748 B.V. Non-Voting Class A Shares, respectively.

F3 · ownership.nature: Baker Hughes Company has an indirect pecuniary interest in the securities held by each of Baker Hughes Holdings LLC. Consequently, Baker Hughes Company may be deemed to share beneficial ownership in the securities held directly by Baker Hughes Holdings LLC. The board of directors and officers of Baker Hughes Company disclaim beneficial ownership with respect to such securities.

F4 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Baker Hughes has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F5 · ownership.nature: Judson E. Bailey and M. Georgia Magno are directors of the Issuer and were nominated for such roles by Baker Hughes Holdings LLC. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Baker Hughes Holdings LLC may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · derivative · entry 8

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Akastor AS

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_price: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_price: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.expiration_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.expiration_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · derivative · entry 7

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Mercury HoldCo Inc.

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_price: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_price: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.expiration_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.expiration_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · derivative · entry 6

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Akastor AS

Disclosed balance after: 0

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_price: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_price: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.expiration_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.expiration_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · derivative · entry 5

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Mercury HoldCo Inc.

Disclosed balance after: 0

Underlying: Class A common stock · 16,288,748 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_price: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_price: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.expiration_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.expiration_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · derivative · entry 4

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Akastor AS

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 1,050,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_price: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_price: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.expiration_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.expiration_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · derivative · entry 3

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Mercury HoldCo Inc.

Disclosed balance after: 16,288,748

Underlying: Class A common stock · 1,050,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_price: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_price: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_price: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.exercise_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.exercise_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.exercise_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.exercise_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · derivative.expiration_date: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · derivative.expiration_date: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · derivative.expiration_date: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · derivative.expiration_date: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · nonDerivative · entry 2

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Akastor AS See footnotes

Disclosed balance after: 16,288,748

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0000950157-26-000464 · form4.xml · nonDerivative · entry 1

Akastor ASA · CIK 0002037057 · 10% owner

Akastor AS · CIK 0002124921 · Director · 10% owner · Director by Deputization

Mercury HoldCo AS · CIK 0002124920 · 10% owner

Mercury HoldCo Inc. · CIK 0002124922 · Director · 10% owner · Director by Deputization

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · Mercury HoldCo Inc. See footnotes

Disclosed balance after: 8,144,374

F1 · kind: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · kind: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · kind: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F5 · kind: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F1 · ownership.nature: Prior to the initial public offering ("IPO") of HMH Holding Inc. (the "Issuer"), (a) Akastor AS, a direct wholly owned subsidiary of Akastor ASA, held 50 Class B ordinary shares (the "B.V. Voting Class B Shares") of HMH Holding B.V. ("HMH B.V.") and (b) Mercury HoldCo Inc., an indirect wholly owned subsidiary of Akastor ASA (with Mercury HoldCo AS as an intermediary subsidiary between Akastor ASA and Mercury HoldCo Inc.) held 50 Class A ordinary shares (the "B.V. Voting Class A Shares") of HMH B.V. In this filing, Akastor ASA, Akastor AS, Mercury HoldCo AS and Mercury HoldCo Inc. are collectively referred to as "Akastor". (cont'd in fn 2)

F2 · ownership.nature: (cont'd from fn 1) In connection with the corporate reorganization and Akastor's participation in the synthetic secondary as described in the Issuer's Registration Statement on Form S-1 (Registration No. 333-281497), the following transactions have occurred: first, HMH B.V., the predecessor entity to the Issuer, underwent a 346,774.96 for 1 stock split, after which Akastor held 17,338,748 B.V. Voting Class B Shares (through Akastor AS) and 17,338,748 B.V. Voting Class A Shares (through Mercury HoldCo Inc.); second, HMH B.V. recapitalized to convert (i) 16,288,748 of Mercury HoldCo Inc.'s B.V. Voting Class A Shares to non-voting Class A ordinary shares (the "B.V. Non-Voting Class A Shares") and (ii) 16,288,748 of Akastor AS's B.V. Voting Class B Shares to non-voting Class B ordinary shares (the "B.V. Non-Voting Class B Shares"); (cont'd in fn 3)

F3 · ownership.nature: (cont'd from fn. 2) third, (i) Akastor AS sold 1,050,000 B.V. Voting Class B Shares, and Mercury HoldCo Inc. sold 1,050,000 B.V. Voting Class A Shares, in each case, to the Issuer in exchange cumulatively for $19,740,000 and (ii) each of Akastor AS and Mercury HoldCo Inc. received 8,144,374 shares of Class B common stock of the Issuer (the "Issuer Class B Shares") in exchange for relinquishing voting rights on their respective remaining 16,288,748 B.V. Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Voting Class A Shares (held by Mercury HoldCo Inc.) that were recapitalized into 16,288,748 B.V. Non-Voting Class B Shares (held by Akastor AS) and 16,288,748 B.V. Non-Voting Class A Shares (held by Mercury HoldCo Inc.), respectively.

F4 · ownership.nature: Akastor ASA has an indirect pecuniary interest in the securities held by each of Akastor AS and Mercury HoldCo Inc. Mercury HoldCo AS has an indirect pecuniary interest in the securities held by Mercury HoldCo Inc. Consequently, Akastor ASA may be deemed to share beneficial ownership in the securities held directly by Akastor AS, and Akastor ASA and Mercury HoldCo AS may be deemed to share beneficial ownership in the securities held directly by Mercury HoldCo Inc. The board of directors and officers of Akastor ASA, Mercury HoldCo Inc., Akastor AS and Mercury HoldCo AS disclaim beneficial ownership with respect to such securities.

F5 · ownership.nature: Pursuant to the Exchange Agreement, dated as of April 2, 2026, by and among the Issuer, HMH B.V. and the other parties thereto, Akastor has the right to exchange one Issuer Class B Share, one B.V. Non-Voting Class A Share and one B.V. Non-Voting Class B Share for cash or shares of the Issuer's Class A common stock on a one-for-one basis, subject to customary conversion rate adjustments (e.g. for stock splits, stock dividends and reclassifications). These rights are exercisable at any time after the conclusion of the Issuer's IPO lock-up period (i.e., September 27, 2026, unless the IPO lock-up is earlier released or waived by the underwriters of the Issuer's IPO) and do not expire.

F6 · ownership.nature: Karl Erik Kjelstad and Svein Oskar Stoknes are directors of the Issuer and were nominated for such roles by Akastor AS and Mercury HoldCo Inc. By virtue of their service on the Board of Directors of the Issuer, for purposes of Section 16, Akastor AS and Mercury HoldCo Inc. may be deemed to be a "director by deputization" of the Issuer.

SEC source: 0001193125-26-143539 · ownership.xml · nonDerivative · entry 1

Stoknes Svein Oskar · CIK 0002116277 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,486

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. (the "Issuer"). The restricted stock units vest on the day prior to the Issuer's first annual meeting of stockholders following the grant date.

SEC source: 0001193125-26-143538 · ownership.xml · nonDerivative · entry 2

Dyrseth Roy A. · CIK 0002035162 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 68,276

F2 · shares: Represents shares of Class A Common Stock purchased by the reporting person through the directed share program conducted in connection with the Issuer's initial public offering.

SEC source: 0001193125-26-143538 · ownership.xml · nonDerivative · entry 1

Dyrseth Roy A. · CIK 0002035162 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 60,276

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share ("Class A Common Stock"), of HMH Holding Inc. (the "Issuer"). The restricted stock units include 46,695 restricted stock units that vested immediately upon grant, 3,018 restricted stock units that vest on September 1, 2026, 4,225 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 6,338 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.

SEC source: 0001193125-26-143529 · ownership.xml · nonDerivative · entry 2

Skogerbo Pal · CIK 0002035218 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 61,276

F2 · shares: Represents shares of Class A Common Stock purchased by the reporting person through the directed share program conducted in connection with the Issuer's initial public offering.

SEC source: 0001193125-26-143529 · ownership.xml · nonDerivative · entry 1

Skogerbo Pal · CIK 0002035218 · Chief Technology Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 60,276

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share ("Class A Common Stock"), of HMH Holding Inc. (the "Issuer"). The restricted stock units include 46,695 restricted stock units that vested immediately upon grant, 3,018 restricted stock units that vest on September 1, 2026, 4,225 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 6,338 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.

SEC source: 0001193125-26-143527 · ownership.xml · nonDerivative · entry 2

Loeffler Lance · CIK 0001759163 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,486

F2 · shares: Represents shares of Class A Common Stock purchased by the reporting person through the directed share program conducted in connection with the Issuer's initial public offering.

SEC source: 0001193125-26-143527 · ownership.xml · nonDerivative · entry 1

Loeffler Lance · CIK 0001759163 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,486

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share ("Class A Common Stock"), of HMH Holding Inc. (the "Issuer"). The restricted stock units vest on the day prior to the Issuer's first annual meeting of stockholders following the grant date.

SEC source: 0001193125-26-143524 · ownership.xml · nonDerivative · entry 2

McGee Thomas W. · CIK 0002035200 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 147,338

F2 · shares: Represents shares of Class A Common Stock purchased by the reporting person through the directed share program conducted in connection with the Issuer's initial public offering.

SEC source: 0001193125-26-143524 · ownership.xml · nonDerivative · entry 1

McGee Thomas W. · CIK 0002035200 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 97,338

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share ("Class A Common Stock"), of HMH Holding Inc. (the "Issuer"). The restricted stock units include 83,757 restricted stock units that vested immediately upon grant, 3,018 restricted stock units that vest on September 1, 2026, 4,225 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 6,338 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.

SEC source: 0001193125-26-143521 · ownership.xml · nonDerivative · entry 1

Qureshi Hunain · CIK 0002035763 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 24,594

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. The restricted stock units include 16,416 restricted stock units that vested immediately upon grant, 845 restricted stock units that vest on September 1, 2026, 5,136 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 2,197 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.

SEC source: 0001193125-26-143512 · ownership.xml · nonDerivative · entry 1

Rabun Daniel Wayne · CIK 0001354803 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 9,900

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. (the "Issuer"). The restricted stock units vest on the day prior to the Issuer's first annual meeting of stockholders following the grant date.

SEC source: 0001193125-26-143514 · ownership.xml · nonDerivative · entry 1

McAllister Kathleen S · CIK 0001614884 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,486

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. (the "Issuer"). The restricted stock units vest on the day prior to the Issuer's first annual meeting of stockholders following the grant date.

SEC source: 0001193125-26-143507 · ownership.xml · nonDerivative · entry 1

RETTIG DWIGHT W · CIK 0001228420 · Chf Admn Officer, GC, Corp Sec

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 97,338

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. The restricted stock units include 83,757 restricted stock units that vested immediately upon grant, 3,018 restricted stock units that vest on September 1, 2026, 4,225 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 6,338 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.

SEC source: 0001193125-26-143505 · ownership.xml · nonDerivative · entry 2

Bergsvik Eirik · CIK 0002035158 · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 121,858

F2 · shares: Represents shares of Class A Common Stock purchased by the reporting person through the directed share program conducted in connection with the Issuer's initial public offering.

SEC source: 0001193125-26-143505 · ownership.xml · nonDerivative · entry 1

Bergsvik Eirik · CIK 0002035158 · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 111,858

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share ("Class A Common Stock"), of HMH Holding Inc. (the "Issuer"). The restricted stock units include 90,127 restricted stock units that vested immediately upon grant, 4,829 restricted stock units that vest on September 1, 2026, 6,761 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 10,141 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.

SEC source: 0001193125-26-143503 · ownership.xml · nonDerivative · entry 1

Kjelstad Karl Erik · CIK 0002037060 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,486

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. (the "Issuer"). The restricted stock units vest on the day prior to the Issuer's first annual meeting of stockholders following the grant date.

SEC source: 0001193125-26-143494 · ownership.xml · nonDerivative · entry 1

CHAUVIERE E CHARLS · CIK 0001240953 · Chief Operations Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 85,478

F1 · shares: Represents restricted stock units granted to the reporting person under the HMH Holding Inc. 2026 Long-Term Incentive Plan on April 2, 2026. Each restricted stock unit represents a contingent right to receive one share of Class A common stock, par value $0.01 per share, of HMH Holding Inc. The restricted stock units include 71,897 restricted stock units that vested immediately upon grant, 3,018 restricted stock units that vest on September 1, 2026, 4,225 restricted stock units that vest in two equal annual installments on September 1, 2026 and September 1, 2027 and 6,338 restricted stock units that vest in three equal annual installments on September 1, 2026, September 1, 2027 and September 1, 2028.