[Form 4] Solid Biosciences Inc. Insider Trading Activity

Rhea-AI Filing Summary

Solid Biosciences Inc. director Ian F. Smith reported receipt of 4,573 restricted stock units that convert one-for-one into common shares. The filing shows the RSUs were granted on 01/06/2025 and, per the grant terms, vest in equal quarterly installments beginning three months after the grant with final vesting 12 months after the grant date. The report records the RSUs as acquired on 10/06/2025 and notes the units accelerate in full if the executive chair agreement terminates early or if there is a change in control. After the transaction the reporting person beneficially owns 126,692 shares of common stock. The filing was signed by an attorney-in-fact on 10/07/2025.

Positive

• Grant of 4,573 restricted stock units aligns director incentives with shareholder value through equity vesting
• RSUs vest over a defined schedule (equal quarterly installments over 12 months), staging dilution rather than immediate issuance

Negative

• Potential acceleration of full RSU vesting on early termination of the executive chair agreement or a change in control, which could cause near‑term dilution
• Reported acquisition recorded at $0.00 per share increases outstanding beneficial ownership without cash consideration

Insights

Corporate Governance Analyst

Director received time‑based RSUs that vest over one year and include change‑of‑control acceleration.

The grant converts one-for-one into common stock and vests quarterly over a 12‑month period from the 01/06/2025 grant date, which stages dilution into the next four quarters rather than immediate issuance. The RSUs are recorded as acquired on 10/06/2025 and carry an exercise/price of $0.00, reflecting typical restricted‑unit treatment rather than a cash purchase.

Acceleration on early termination of the executive chair agreement or a change in control creates a contingent immediate issuance risk for shareholders; monitor outstanding share count changes across the next 12/2025 quarter for the near‑term dilution effect and any corporate events that could trigger acceleration.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

SMITH IAN F

(Last) (First) (Middle)

C/O SOLID BIOSCIENCES INC.

500 RUTHERFORD AVENUE, THIRD FLOOR

(Street)

CHARLESTOWN MA 02129

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Solid Biosciences Inc. [ SLDB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
10/06/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/06/2025		M		4,573	A	(1)	126,692	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(1)	10/06/2025		M			4,573	(2)	(2)	Common Stock	4,573	$0.00	4,573	D

Explanation of Responses:

1. Restricted stock units convert to common stock on a one-for-one basis.

2. The restricted stock units were granted on January 6, 2025 (the "Grant Date") and vest in equal quarterly installments beginning three months from the Grant Date, with the final installment vesting the date that is 12 months from the Grant Date; provided that in the event of the early termination of the Third Amendment to Executive Chair Agreement between the Issuer and the reporting person (the "Smith Agreement") prior to the expiration of the Term (as defined in the Smith Agreement) and/or a change in control of the Issuer, the restricted stock units shall accelerate in full.

	/s/ David Tyronne Howton as attorney-in-fact for Ian F. Smith	10/07/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What did Ian F. Smith report on the SLDB Form 4?

The report discloses acquisition of 4,573 restricted stock units that convert one-for-one to common stock and are reflected as acquired on 10/06/2025.

When do the RSUs granted to Ian F. Smith vest?

The RSUs were granted on 01/06/2025 and vest in equal quarterly installments beginning three months after the grant, with final vesting at 12 months.

How many shares does Ian F. Smith beneficially own after the transaction?

After the reported transaction the filing shows beneficial ownership of 126,692 shares of common stock.

Is there any special acceleration or change‑of‑control provision?

Yes. The RSUs accelerate in full if the Third Amendment to the Executive Chair Agreement terminates early or if there is a change in control.

Was there a cash price for the RSUs?

No. The reported price is $0.00, consistent with restricted stock units rather than a cash purchase.