[Form 4] Solid Biosciences Inc. Insider Trading Activity

Rhea-AI Filing Summary

Solid Biosciences (SLDB) Form 4: Chief Medical Officer Gabriel Brooks reported RSU vesting and a related tax sale. On 10/18/2025, 9,750 restricted stock units converted to common stock on a one-for-one basis. On 10/20/2025, 2,895 shares were sold at $5.96 to cover withholding taxes under a previously adopted durable automatic sale instruction letter, characterized as a sell-to-cover and not a discretionary trade.

Following these transactions, Brooks beneficially owned 33,819 common shares, held directly. The filing notes an additional 19,500 RSUs beneficially owned after the reported transactions. The RSU grant from 10/18/2023 vests over four years at 25% on each anniversary of the grant date.

Insights

Insider transactions analyst

Routine RSU vesting with tax sell-to-cover; neutral signal.

The report shows 9,750 RSUs converting to common on 10/18/2025 and a sell-to-cover of 2,895 shares at $5.96 on 10/20/2025. The sale is attributed to withholding taxes under a durable automatic sale instruction letter.

These mechanics are typical for equity compensation and do not indicate discretionary selling pressure. After the transactions, direct ownership stands at 33,819 common shares, with 19,500 RSUs remaining from the 10/18/2023 grant that vests 25% annually.

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^*

Brooks Gabriel

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
10/18/2025

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	10/18/2025		M		9,750	A	(1)	36,714(2)	D
Common Stock	10/20/2025		S		2,895(3)	D	$5.96	33,819	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)	10/18/2025		M			9,750	(4)	(4)	Common Stock	9,750	$0	19,500	D

Explanation of Responses:

1. Restricted stock units ("RSUs") convert into common stock on a one-for-one basis.

2. Includes 4,152 shares of common stock acquired under the Solid Biosciences Inc. Employee Stock Purchase Plan on May 30, 2025.

3. This sale was made to cover withholding taxes following the vesting of previously granted RSUs pursuant to a durable automatic sale instruction letter adopted by Dr. Brooks on August 15, 2024 effecting the sell-to-cover election. The sale does not represent a discretionary trade by Dr. Brooks.

4. The RSUs were granted on October 18, 2023 (the "Grant Date") and vest over four years, with 25% of the original number of shares vesting on each anniversary of the Grant Date until the fourth such anniversary.

	/s/ Kimberly Cornwell as attorney-in-fact for Gabriel Brooks	10/21/2025
	** 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 SLDB’s CMO report on this Form 4?

Vesting of 9,750 RSUs on 10/18/2025 and a tax-related sale of 2,895 shares at $5.96 on 10/20/2025.

How many SLDB shares does the reporting person own after the transactions?

Direct beneficial ownership is 33,819 common shares after the reported transactions.

Was the SLDB share sale discretionary?

No. The sale covered withholding taxes under a durable automatic sale instruction letter and is described as non-discretionary.

What RSU balance remains for the SLDB CMO?

The filing lists 19,500 RSUs beneficially owned after the reported transactions.

What is the SLDB RSU vesting schedule?

The RSUs granted on 10/18/2023 vest over four years at 25% on each anniversary of the grant date.

What price were the SLDB shares sold for tax withholding?

Shares were sold at $5.96 per share on 10/20/2025.