SCHEDULE 13D/A 0001224962 XXXXXXXX LIVE 9 Common Stock, $0.001 par value per share 03/09/2026 false 0001707502 83422E204 Solid Biosciences Inc.

500 Rutherford Avenue Third Floor Charlestown MA 02129

Perceptive Advisors LLC 646-205-5345 Alexander Rakitin, 51 Astor Place, 10th Floor New York NY 10003 0001224962 N Perceptive Advisors LLC b AF Y DE 0 11969079 0 11969079 11969079 N 12.9 IA 0001164426 N Joseph Edelman b AF Y X1 0 11969079 0 11969079 11969079 N 12.9 IN 0001249675 N Perceptive Life Sciences Master Fund, Ltd. b WC Y E9 0 11895972 0 11895972 11895972 N 12.8 CO 0001757940 N Perceptive Xontogeny Venture Fund, LP b WC Y DE 0 73107 0 73107 73107 N 0.1 CO Common Stock, $0.001 par value per share Solid Biosciences Inc. 500 Rutherford Avenue Third Floor Charlestown MA 02129 The shares of Common Stock set forth below in Item 5(c) of this Amendment No. 9 to Schedule 13D were acquired with working capital of the Master Fund. The information set forth in Item 6 below in this Amendment No. 9 to Schedule 13D is incorporated by reference. The information set forth in rows 11 and 13 of the cover pages to this Schedule 13D is incorporated by reference. The percentages set forth in rows 13 are based on an aggregate of 92,883,496 shares of Common Stock outstanding, consisting of (i) 77,910,239 shares of Common Stock outstanding as of October 29, 2025, as disclosed by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (the "SEC") on November 3, 2025, and (ii) 14,973,257 shares of Common Stock issued in the Issuer's private placement on March 9, 2026, as reported by the Issuer in its Current Report on Form 8-K filed with the SEC on March 6, 2026. The information set forth in rows 7 through 10 of the cover pages to this Schedule 13D is incorporated by reference. Adam Stone, the Chief Investment Officer of the Advisor, holds stock options for a total of 139,933 shares of Common Stock, of which 62,433 are currently exercisable, or exercisable within 60 days. The Master Fund has the right to receive the director compensation provided in respect of Mr. Stone's board service through a partial management fee offset. On March 9, 2026, pursuant to a private placement conducted by the Issuer (the "Private Placement"), the Master Fund acquired 8,912,655 pre-funded warrants to purchase shares of the Issuer's Common Stock (the "Pre-Funded Warrants"), at a price of $5.609 per Pre-Funded Warrant, for an aggregate purchase price of $49.9 million. The terms of the Pre-Funded Warrants provide that the Pre-Funded Warrants may not be exercised if, after giving effect to such exercise, the Reporting Persons would beneficially own, as determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended, more than 9.99% of the shares of Common Stock then issued and outstanding. As a result of the beneficial ownership limitation described above, the Reporting Persons are currently unable to exercise any of the Pre-Funded Warrants. Securities Purchase Agreement On March 6, 2026, the Master Fund and certain other institutional investors entered into a securities purchase agreement (the "Securities Purchase Agreement") with the Issuer, pursuant to which the Master Fund acquired 8,912,655 pre-funded warrants to purchase shares of Common Stock at a price of $5.609 per pre-funded warrant. The Private Placement closed on March 9, 2026. Registration Rights Agreement Also on March 6, 2026, the Master Fund entered into a registration rights agreement (the "Registration Rights Agreement") with the Issuer, pursuant to which the Issuer agreed to register for resale the shares of Common Stock issuable upon exercise of the Pre-Funded Warrants acquired by the Master Fund pursuant to the Securities Purchase Agreement. The foregoing descriptions of the Securities Purchase Agreement, the Registration Rights Agreement and the Pre-Funded Warrant are qualified in their entirety by reference to the full text of the forms of Securities Purchase Agreement, the Registration Rights Agreement and the Pre-Funded Warrant, copies of which are filed as Exhibits 14, 15, and 16 hereto. Exhibit 14 Form of Securities Purchase Agreement, dated March 6, 2026 (incorporated by reference from Exhibit 10.1 to the Issuer's Current Report on Form 8-K filed with the SEC on March 6, 2026) Exhibit 15 Form of Registration Rights Agreement, dated March 6, 2026 (incorporated by reference from Exhibit 10.2 to the Issuer's Current Report on Form 8-K filed with the SEC on March 6, 2026) Exhibit 16 Form of Pre-Funded Warrant (incorporated by reference from Exhibit 4.1 to the Issuer's Current Report on Form 8-K filed with the SEC on March 6, 2026) Perceptive Advisors LLC /s/ Joseph Edelman 03/11/2026 Joseph Edelman /s/ Joseph Edelman 03/11/2026 Perceptive Life Sciences Master Fund, Ltd. /s/ Joseph Edelman 03/11/2026 Perceptive Xontogeny Venture Fund, LP /s/ Joseph Edelman 03/11/2026