XE

SEC source: 0001193125-26-272938 · ownership.xml · nonDerivative · entry 1

Ghaffarian Kamal Seyed · CIK 0001963529 · Director · 10% owner

X-Energy Holdings, LLC · CIK 0002131792 · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnote

Disclosed balance after: 5,308,515

F1 · kind: On June 12, 2026, IBX, LLC perfected its security interest in 279,438 shares of the Issuer's Class A Common Stock to secure the payment in full of the amount owed to it under a non-negotiable promissory note made by an unaffiliated third party in favor of IBX, LLC and gave notice of default to such third party. On that date, the outstanding amount due under the note was $3,727,858. The balance owed under the note will increase at the rate of $1,414.00 per day, plus costs and expenses of collection. Based on the closing price for such shares on NASDAQ on June 12, 2026, of $18.59 per share, 200,530 shares would have been required to satisfy the note on that date. However, upon the actual transfer of the shares of the Issuer's Class A Common Stock, the number of shares transferred to satisfy the then-outstanding amount under the note may be different from that number up to 279,438 shares.

F1 · price: On June 12, 2026, IBX, LLC perfected its security interest in 279,438 shares of the Issuer's Class A Common Stock to secure the payment in full of the amount owed to it under a non-negotiable promissory note made by an unaffiliated third party in favor of IBX, LLC and gave notice of default to such third party. On that date, the outstanding amount due under the note was $3,727,858. The balance owed under the note will increase at the rate of $1,414.00 per day, plus costs and expenses of collection. Based on the closing price for such shares on NASDAQ on June 12, 2026, of $18.59 per share, 200,530 shares would have been required to satisfy the note on that date. However, upon the actual transfer of the shares of the Issuer's Class A Common Stock, the number of shares transferred to satisfy the then-outstanding amount under the note may be different from that number up to 279,438 shares.

F2 · ownership.nature: Consists of (i) 471,774 shares of Class A Common Stock held by GM Enterprises, LLC, (ii) 3,951,679 shares of Class A Common Stock held by X-Energy Holdings, LLC, (iii) 12,973 shares of Class A Common Stock held by IBX Opportunity GP, Inc., (iv) 592,651 shares of Class A Common Stock held by X-energy KG Parent, LLC and (v) 279,438 shares of Class A Common Stock held by IBX, LLC. Dr. Kamal Ghaffarian has sole voting and dispositive power with respect to securities held by each of the foregoing entities. Dr. Kamal Ghaffarian disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.

SEC source: 0001193125-26-255430 · ownership.xml · derivative · entry 2

Gross Daniel Andrew · CIK 0001735871 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,605,770

Underlying: Class A Common Stock · 332,615 shares

Expires 2036-06-01

F2 · derivative.exercise_date: The stock options vest in four substantially equal annual installments beginning on December 23, 2026.

SEC source: 0001193125-26-255430 · ownership.xml · nonDerivative · entry 1

Gross Daniel Andrew · CIK 0001735871 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,025,183

F1 · shares: Represents a grant of restricted stock units ("RSUs"). Each RSU represents a right to receive one share of the Issuer's Class A common stock upon vesting. The RSUs vest in four substantially equal annual installments beginning on December 23, 2026.

SEC source: 0001193125-26-255435 · ownership.xml · nonDerivative · entry 1

GARCIA LAURA · CIK 0001994716 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 240,300

F1 · shares: Represents a grant of restricted stock units ("RSUs"). Each RSU represents a right to receive one share of the Issuer's Class A common stock upon vesting. The RSUs vest in three subtantially equal annual installments beginning on the first anniversary of the grant date.

SEC source: 0001117310-26-000005 · ownership.xml · nonDerivative · entry 2

HYLE KATHLEEN W · CIK 0001117310 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 134,162

F2 · price: Each restricted stock unit ("RSU") represents the right to receive one share of Class A common stock. The RSUs will vest on the earlier to occur of (x) April 27, 2027 and (y) the date of the 2027 Annual Meeting, subject to continued service.

F3 · balance_after: Includes 29,410 shares of restricted stock.

SEC source: 0001164695-26-000005 · ownership.xml · nonDerivative · entry 2

Wallace Michael J Wallace · CIK 0001164695 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 77,683

F2 · price: Each restricted stock unit ("RSU") represents the right to receive one share of Class A common stock. The RSUs will vest on the earlier to occur of (x) April 27, 2027 and (y) the date of the 2027 Annual Meeting, subject to continued service.

F3 · balance_after: Includes 17,540 shares of restricted stock.

SEC source: 0001490987-26-000003 · ownership.xml · nonDerivative · entry 1

Goff Gregory James · CIK 0001490987 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 124,162

F1 · price: Each restricted stock unit ("RSU") represents the right to receive one share of Class A common stock. The RSUs will vest on the earlier to occur of (x) April 27, 2027 and (y) the date of the 2027 Annual Meeting, subject to continued service.

F2 · balance_after: Includes 16,750 shares of restricted stock.

SEC source: 0001963529-26-000004 · ownership.xml · nonDerivative · entry 1

Ghaffarian Kamal Seyed · CIK 0001963529 · Director · 10% owner

X-Energy Holdings, LLC · CIK 0002131792 · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,240,543

F1 · price: Each restricted stock unit ("RSU") represents the right to receive one share of Class A common stock. The RSUs will vest on the earlier to occur of (x) April 27, 2027 and (y) the date of the 2027 Annual Meeting, subject to continued service.

SEC source: 0001995078-26-000003 · ownership.xml · nonDerivative · entry 1

GINTHER CHRISTOPHER · CIK 0001995078 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 124,162

F1 · price: Each restricted stock unit ("RSU") represents the right to receive one share of Class A common stock. The RSUs will vest on the earlier to occur of (x) April 27, 2027 and (y) the date of the 2027 Annual Meeting, subject to continued service.

F2 · balance_after: Includes 16,750 shares of restricted stock.

SEC source: 0001995008-26-000003 · ownership.xml · nonDerivative · entry 1

SONNENSCHEIN EDWARD · CIK 0001995008 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 820,114

F1 · price: Each restricted stock unit ("RSU") represents the right to receive one share of Class A common stock. The RSUs will vest on the earlier to occur of (x) April 27, 2027 and (y) the date of the 2027 Annual Meeting, subject to continued service.

F2 · balance_after: Includes 17,540 shares of restricted stock.

SEC source: 0001117310-26-000005 · ownership.xml · nonDerivative · entry 1

HYLE KATHLEEN W · CIK 0001117310 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 127,640

F1 · shares: Shares acquired pursuant to a Directed Share Program in connection with the initial public offering of X-Energy, Inc.

SEC source: 0001164695-26-000005 · ownership.xml · nonDerivative · entry 1

Wallace Michael J Wallace · CIK 0001164695 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 71,161

F1 · shares: Shares acquired pursuant to a Directed Share Program in connection with the initial public offering of X-Energy, Inc.

SEC source: 0001994716-26-000004 · ownership.xml · nonDerivative · entry 1

GARCIA LAURA · CIK 0001994716 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 196,822

F1 · shares: Shares acquired pursuant to a Directed Share Program in connection with the initial public offering of X-Energy, Inc.

F2 · balance_after: Includes 75,254 shares of restricted stock.

SEC source: 0002111843-26-000004 · ownership.xml · nonDerivative · entry 1

Duling Joel · CIK 0002111843 · President, TRISO-X

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 552,699

F1 · shares: Shares acquired pursuant to a Directed Share Program in connection with the initial public offering of X-Energy, Inc.