GWH

SEC source: 0000899243-21-044447 · doc4.xml · nonDerivative · entry 4

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 85,225

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F6 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 11,577 shares of Issuer common stock pursuant to the Earnout Rights and 93 shares of Issuer common stock pursuant to the Expense Shortfall.

F8 · ownership.nature: The shares are held of record by the Ian M. Niggli 2021 Gift Trust for which the reporting person serves as trustee.

SEC source: 0000899243-21-044447 · doc4.xml · nonDerivative · entry 3

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 85,225

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F6 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 11,577 shares of Issuer common stock pursuant to the Earnout Rights and 93 shares of Issuer common stock pursuant to the Expense Shortfall.

F7 · ownership.nature: The shares are held of record by the Chloe D. Niggli Gift Trust for which the reporting person serves as trustee.

SEC source: 0000899243-21-044447 · doc4.xml · nonDerivative · entry 2

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 227,400

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F4 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 30,891 shares of Issuer common stock pursuant to the Earnout Rights and 249 shares of Issuer common stock pursuant to the Expense Shortfall.

F5 · ownership.nature: The shares are held of record by the Michael R. Niggli Family Trust for which the reporting person serves as trustee.

SEC source: 0000899243-21-044447 · doc4.xml · nonDerivative · entry 1

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 480,166

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F3 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 65,228 shares of Issuer common stock pursuant to the Earnout Rights and 524 shares of Issuer common stock pursuant to the Expense Shortfall.

SEC source: 0000899243-21-045199 · doc4.xml · nonDerivative · entry 2

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 2,278,031

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

F2 · ownership.nature: The shares are held directly by Julia Song. The reporting persons are husband and wife.

SEC source: 0000899243-21-045199 · doc4.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,391,684

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-045096 · doc4a.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,332,700

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F3 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 724,426 shares of Issuer common stock pursuant to the Earnout Rights and 5,821 shares of Issuer common stock pursuant to the Expense Shortfall.

SEC source: 0000899243-21-045197 · doc4.xml · nonDerivative · entry 1

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 568,302

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein). Effective as of November 9, 2021, the reporting person was entitled to receive 77,201 shares of Issuer common stock pursuant to the Earnout Rights and 621 shares of Issuer common stock pursuant to the Expense Shortfall.

F3 · ownership.nature: The shares are held of record by the Linda Naviaux Niggli Trust for which the reporting person's spouse serves as trustee.

SEC source: 0000899243-21-040096 · doc4.xml · derivative · entry 2

Shadrick-Wilson Ryan D · CIK 0001823101 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 50,000 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.exercise_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.expiration_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.underlying_shares: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · balance_after: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

SEC source: 0000899243-21-040096 · doc4.xml · nonDerivative · entry 1

Shadrick-Wilson Ryan D · CIK 0001823101 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 50,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Ryan Shadrick Wilson's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

SEC source: 0000899243-21-040095 · doc4.xml · derivative · entry 2

Levy Sarah Kirshbaum · CIK 0001786657 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 50,000 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.exercise_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.expiration_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.underlying_shares: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · balance_after: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

SEC source: 0000899243-21-040095 · doc4.xml · nonDerivative · entry 1

Levy Sarah Kirshbaum · CIK 0001786657 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 50,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Sarah Kirshbaum Levy's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

SEC source: 0000899243-21-040099 · doc4.xml · derivative · entry 2

Goddard Janie · CIK 0001823111 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 50,000 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.exercise_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.expiration_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · derivative.underlying_shares: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · balance_after: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

SEC source: 0000899243-21-040099 · doc4.xml · nonDerivative · entry 1

Goddard Janie · CIK 0001823111 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 50,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

F1 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc., a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc." ("New ESS"). In connection with the consummation of the Business Combination, 50,000 of Janie Goddard's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares, par value $0.0001, of the Company converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination.

SEC source: 0000899243-21-040094 · doc4.xml · derivative · entry 3

ACON S2 Sponsor, L.L.C. · CIK 0001819440 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,083,334

Underlying: Common Stock · 4,083,334 shares

Expires not disclosed

F4 · derivative.exercise_price: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F4 · kind: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F4 · price: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F4 · derivative.exercise_date: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F4 · derivative.expiration_date: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F4 · derivative.underlying_shares: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F4 · balance_after: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F1 · ownership.direct: 6,100,000 shares of common stock, par value $0.0001 ("New ESS Common Stock"), of New ESS (as defined below) are held directly by ACON S2 Sponsor, L.L.C., a Delaware limited liability company (the "Sponsor"). Sponsor has voting and investment discretion with respect to the securities held by the Sponsor, and thus may be deemed to have beneficial ownership of such securities. ACON S2 Management, LLC (the "Management") expressly disclaims any such beneficial ownership of such securities, except to the extent of their individual pecuniary interests therein. The business address of Sponsor and Management is 1133 Connecticut Avenue, NW, Suite 700, Washington, DC 20036.

F4 · ownership.direct: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

SEC source: 0000899243-21-040094 · doc4.xml · derivative · entry 2

ACON S2 Sponsor, L.L.C. · CIK 0001819440 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 6,100,000 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · derivative.exercise_price: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F2 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · kind: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F2 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · price: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F2 · derivative.exercise_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · derivative.exercise_date: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F2 · derivative.expiration_date: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · derivative.expiration_date: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F4 · derivative.underlying_shares: In connection with the consummation of the Business Combination, 4,083,334 of the private placement warrants of the Company ("ACON Private Placement Warrants") held by Sponsor, which previously entitled Sponsor to purchase one Class A Ordinary Share at a price of $11.50 per whole share at any time commencing on the later of one year from the closing of the Company's initial public offering or 30 days after the completion of an initial business combination of the Company, were converted into private placement warrants of ESS (each a "New ESS Private Placement Warrant") simultaneously with the closing of the Business Combination, with each whole New ESS Private Placement Warrant entitling the holder thereof to the right to purchase one share of New ESS Common Stock.

F2 · balance_after: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · balance_after: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F1 · ownership.direct: 6,100,000 shares of common stock, par value $0.0001 ("New ESS Common Stock"), of New ESS (as defined below) are held directly by ACON S2 Sponsor, L.L.C., a Delaware limited liability company (the "Sponsor"). Sponsor has voting and investment discretion with respect to the securities held by the Sponsor, and thus may be deemed to have beneficial ownership of such securities. ACON S2 Management, LLC (the "Management") expressly disclaims any such beneficial ownership of such securities, except to the extent of their individual pecuniary interests therein. The business address of Sponsor and Management is 1133 Connecticut Avenue, NW, Suite 700, Washington, DC 20036.

F2 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · ownership.direct: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

SEC source: 0000899243-21-040094 · doc4.xml · nonDerivative · entry 1

ACON S2 Sponsor, L.L.C. · CIK 0001819440 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,100,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · kind: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · kind: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F2 · price: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · price: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

F1 · ownership.direct: 6,100,000 shares of common stock, par value $0.0001 ("New ESS Common Stock"), of New ESS (as defined below) are held directly by ACON S2 Sponsor, L.L.C., a Delaware limited liability company (the "Sponsor"). Sponsor has voting and investment discretion with respect to the securities held by the Sponsor, and thus may be deemed to have beneficial ownership of such securities. ACON S2 Management, LLC (the "Management") expressly disclaims any such beneficial ownership of such securities, except to the extent of their individual pecuniary interests therein. The business address of Sponsor and Management is 1133 Connecticut Avenue, NW, Suite 700, Washington, DC 20036.

F2 · ownership.direct: Pursuant to the Agreement and Plan of Merger, dated May 6, 2021, by and among ACON S2 Acquisition Corp., a Cayman Islands exempted company (the "Company"), SCharge Merger Sub, Inc., a Delaware corporation, and ESS Tech, Inc, a Delaware corporation ("ESS"), the parties effected a business combination transaction ("Business Combination"), on October 8, 2021. In connection with the Business Combination, the Company domesticated as a Delaware corporation (the "Domestication") and changed its name to "ESS Tech, Inc" ("New ESS"). In connection with the consummation of the Business Combination, 6,100,000 of Sponsor's Class B ordinary shares, par value $0.0001, of the Company, which were previously convertible into Class A ordinary shares,

F3 · ownership.direct: (Continued from footnote 2) par value $0.0001, of the Company ("Class A ordinary shares") converted into shares of common stock, par value $0.0001, of New ESS simultaneously with the closing of the Business Combination. After giving effect to this transaction, Management will own less than 10% of the outstanding common stock of New ESS.

SEC source: 0000899243-20-031332 · doc4.xml · derivative · entry 1

ACON S2 Management, LLC · CIK 0001819440 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,100,000

Underlying: Class A ordinary shares · 937,500 shares

Expires not disclosed

F1 · derivative.exercise_price: This Form 4 reflects the automatic surrender to ACON S2 Acquisition Corp. (the "issuer") of 937,500 shares of the issuer's Class B ordinary shares, par value $0.0001 per share, for no consideration by the reporting person pursuant to contractual arrangements with the issuer, triggered by the election by the underwriter of the issuer's initial public offering to not exercise its option to purchase additional units.

F1 · kind: This Form 4 reflects the automatic surrender to ACON S2 Acquisition Corp. (the "issuer") of 937,500 shares of the issuer's Class B ordinary shares, par value $0.0001 per share, for no consideration by the reporting person pursuant to contractual arrangements with the issuer, triggered by the election by the underwriter of the issuer's initial public offering to not exercise its option to purchase additional units.

F2 · price: As described in the issuer's registration statement on Form S-1 (File No. 333-248515) under the heading "Description of Securities--Founder Shares", the Class B ordinary shares, par value $0.0001 per share, will automatically convert into Class A ordinary shares, par value $0.0001 per share, of the issuer at the time of the issuer's initial business combination, on a one-for-one basis, subject to adjustment for share splits, share capitalizations, reorganizations, recapitalizations and the like, and certain anti-dilution rights and have no expiration date.

F2 · derivative.exercise_date: As described in the issuer's registration statement on Form S-1 (File No. 333-248515) under the heading "Description of Securities--Founder Shares", the Class B ordinary shares, par value $0.0001 per share, will automatically convert into Class A ordinary shares, par value $0.0001 per share, of the issuer at the time of the issuer's initial business combination, on a one-for-one basis, subject to adjustment for share splits, share capitalizations, reorganizations, recapitalizations and the like, and certain anti-dilution rights and have no expiration date.

F2 · derivative.expiration_date: As described in the issuer's registration statement on Form S-1 (File No. 333-248515) under the heading "Description of Securities--Founder Shares", the Class B ordinary shares, par value $0.0001 per share, will automatically convert into Class A ordinary shares, par value $0.0001 per share, of the issuer at the time of the issuer's initial business combination, on a one-for-one basis, subject to adjustment for share splits, share capitalizations, reorganizations, recapitalizations and the like, and certain anti-dilution rights and have no expiration date.