Alexander Cumbo - 29 Jan 2026 Form 4 Insider Report for Solid Biosciences Inc. (SLDB)

Reporting relationship: President and CEO, Director
Issuer ticker: SLDB
Reported as of: 29 Jan 2026
Net transaction value: -$516,613
SEC form: 4
Accepted by SEC: 02 Feb 2026, 20:16:31 UTC
Prior SEC filing: 04 Dec 2025
Next SEC filing: 06 Feb 2026
Source filing: View source filing
Reporting owner signature: /s/ Kimberly Cornwell as attorney-in-fact for Alexander Cumbo

Key filing fact

Alexander Cumbo filed Form 4 for Solid Biosciences Inc. (SLDB) on 02 Feb 2026.

Key facts

This page summarizes Alexander Cumbo's Form 4 filing for Solid Biosciences Inc. (SLDB).
7 reported transactions and 4 derivative rows are listed below.
Accepted by SEC: 02 Feb 2026, 20:16.

Change

Previous filing in this sequence was filed on 04 Dec 2025.
Current net transaction value: -$516,613.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001685994 Primary reporting owner

Cumbo Alexander

Relationship: President and CEO, Director
Address: C/O SOLID BIOSCIENCES INC., 500 RUTHERFORD AVENUE, THIRD FLOOR, CHARLESTOWN
Signature: /s/ Kimberly Cornwell as attorney-in-fact for Alexander Cumbo
Signature date: 02 Feb 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

SLDB transaction

Common Stock

Options Exercise

Transaction value
Shares: +169,401
Change %: +208%
Price
Shares after: 250,789
Date: 29 Jan 2026
Ownership: Direct
Footnotes: F1

SLDB transaction

Common Stock

Options Exercise

Transaction value
Shares: +100,400
Change %: +40%
Price
Shares after: 351,189
Date: 31 Jan 2026
Ownership: Direct
Footnotes: F2

SLDB transaction

Common Stock

Sale

Transaction value: $516,613
Shares: -80,258
Change %: -23%
Price: $6.44
Shares after: 270,931
Date: 02 Feb 2026
Ownership: Direct
Footnotes: F3, F4

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

SLDB transaction Derivative

Performance Stock Units

Options Exercise

Transaction value: $0
Shares: -169,401
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 29 Jan 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 169,401
Exercise price
Footnotes: F1, F5

SLDB transaction Derivative

Employee Stock Option (Right to Buy)

Award

Transaction value: $0
Shares: +509,850
Change %
Price: $0.000000
Shares after: 509,850
Date: 29 Jan 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 509,850
Exercise price: $6.60
Footnotes: F6

SLDB transaction Derivative

Restricted Stock Units

Award

Transaction value: $0
Shares: +254,900
Change %
Price: $0.000000
Shares after: 254,900
Date: 29 Jan 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 254,900
Exercise price
Footnotes: F2, F7

SLDB transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value: $0
Shares: -100,400
Change %: -25%
Price: $0.000000
Shares after: 301,200
Date: 31 Jan 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 100,400
Exercise price
Footnotes: F2, F8

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 8 footnotes

Footnote F1

Each performance stock unit ("PSUs") converts to common stock on a one-for-one basis.

Footnote F2

Each restricted stock unit ("RSUs") converts to common stock on a one-for-one basis.

Footnote F3

This sale was made to cover withholding taxes following the vesting of previously granted PSUs 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.

Footnote F4

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.295 to $6.580, 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.

Footnote F5

The PSUs were granted on June 11, 2024 and provide for the vesting of 25% of the target number of underlying RSUs granted upon the achievement of each of four independent performance milestones predetermined by the Board ("Performance Milestones"), subject to the grantee's continued service with the Company (the "Approval Conditions"). The Performance Milestones are tied to the achievement of certain business objectives, as certified by the Board on specified evaluation dates, and are non-market and non-financial in nature. The performance criteria specified for the first Performance Milestone was determined to be met on January 29, 2026 (the "2026 Grant Date") resulting in the vesting of the PSUs as to 25% of the underlying shares.

Footnote F6

This option was granted on the 2026 Grant Date and vests over four years, with 25% of the original number of shares vesting on the first anniversary of the 2026 Grant Date and 2.0833% of the original number of shares monthly thereafter until the fourth such anniversary.

Footnote F7

The RSUs were granted on the 2026 Grant Date and vest over four years, with 25% of the original number of shares vesting on each anniversary of the 2026 Grant Date until the fourth such anniversary.

Footnote F8

On January 31, 2025 (the "2025 Grant Date"), the reporting person was granted 401,600 RSUs, with 25% of the original number of shares vesting on each anniversary of the 2025 Grant Date until the fourth such anniversary.