Solid Biosciences (SLDB) CEO sells 48,913 shares to cover RSU taxes

Rhea-AI Filing Summary

Solid Biosciences Inc. President and CEO Alexander Cumbo reported an automatic sale of common stock tied to tax withholding. On February 4, 2026, he sold 48,913 shares of Solid Biosciences common stock at a weighted average price of $6.4419 per share.

The filing explains this was a sell-to-cover transaction to satisfy withholding taxes after previously granted restricted stock units vested, executed under a durable automatic sale instruction letter adopted on August 18, 2024. After this activity, Cumbo directly beneficially owned 222,018 common shares.

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).

X

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^*

Cumbo Alexander

(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
X	Officer (give title below)		Other (specify below)
	President and CEO

3. Date of Earliest Transaction (Month/Day/Year)
02/04/2026

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	02/04/2026		S		48,913(1)	D	$6.4419(2)	222,018	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

Explanation of Responses:

1. This sale was made to cover withholding taxes following the vesting of previously granted restricted stock units pursuant to a durable automatic sale instruction letter adopted by Mr. Cumbo on August 18, 2024 effecting the sell-to-cover election. The sale does not represent a discretionary trade by Mr. Cumbo.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.28 to $6.60, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in footnote (4) to this Form.

	/s/ Kimberly Cornwell as attorney-in-fact for Alexander Cumbo	02/06/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transaction did Solid Biosciences (SLDB) report for Alexander Cumbo?

Alexander Cumbo reported an automatic sale of 48,913 Solid Biosciences shares. The common stock was sold on February 4, 2026 at a weighted average price of $6.4419 per share, related to tax withholding following the vesting of restricted stock units under a pre-set instruction.

Why did Solid Biosciences (SLDB) CEO Alexander Cumbo sell 48,913 shares?

The shares were sold to cover withholding taxes on vested restricted stock units. The transaction followed a durable automatic sale instruction letter adopted on August 18, 2024, so the sale was part of a pre-arranged sell-to-cover election rather than a discretionary open-market decision.

At what price were the 48,913 Solid Biosciences (SLDB) shares sold by the CEO?

The 48,913 shares were sold at a weighted average price of $6.4419. According to the filing, the sale occurred in multiple trades within a price range from $6.28 to $6.60 per share, with detailed breakdowns available upon request from the reporting person.

How many Solid Biosciences (SLDB) shares does CEO Alexander Cumbo own after the sale?

After the reported tax-related sale, Cumbo beneficially owns 222,018 shares. These are common shares held directly following the February 4, 2026 transaction, as disclosed in the Form 4, reflecting his remaining equity stake as president and chief executive officer.

Was the Solid Biosciences (SLDB) CEO’s share sale a discretionary trade?

The filing states the sale does not represent a discretionary trade. It was executed under a durable automatic sale instruction letter to cover withholding taxes on previously granted restricted stock units that vested, indicating the transaction followed a pre-established sell-to-cover arrangement.