RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. filed Amendment No. 14 to their Schedule 13D on November 6, 2026, reporting a 10.8% beneficial ownership position in Solid Biosciences Inc. following dilution of their stake, with no acquisition or disposition of securities by the reporting persons.

Key Highlights

  • Filing trigger: The amendment was filed to report dilution of the reporting persons' beneficial ownership, "not as a result of any acquisition or disposition of securities by the Reporting Persons," according to the filing.
  • Aggregate beneficial ownership: RA Capital Management, Peter Kolchinsky, and Rajeev Shah each report 12,036,126 shares beneficially owned, representing 10.8% of the class.
  • Fund-level ownership: RA Capital Healthcare Fund, L.P. separately reports 11,897,896 shares, representing 10.7% of the class.
  • Ownership composition: Holdings consist of 11,897,896 shares held directly by the Fund, 109,661 shares held by the RA Capital Nexus Fund, L.P., 28,569 shares held in a separately managed account, and pre-funded warrants exercisable for up to 8,178,412 shares held by the Fund.
  • Beneficial Ownership Blocker: The pre-funded warrants include a provision precluding exercise if it would result in the Fund and its affiliates owning more than 9.99% of common stock outstanding; the Fund is currently prohibited from exercising those warrants.
  • Triggering event date: The date of the event requiring this filing is listed as 11/04/2026.

RA Capital's Ownership Position in Solid Biosciences Following Dilution

According to the filing, this Amendment No. 14 supplements a Schedule 13D originally filed with the SEC on February 9, 2018, and subsequently amended thirteen times, most recently on June 24, 2026. The reporting persons - RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. - are filing jointly pursuant to Rule 13d-1(k) of the Securities Exchange Act of 1934. The filing discloses that the amendment was prompted solely by dilution of the reporting persons' ownership percentage in Solid Biosciences Inc. common stock.

The filing states that the aggregate beneficial ownership of 12,036,126 shares attributed to RA Capital Management, Dr. Kolchinsky, and Mr. Shah is composed of four components: 11,897,896 shares held directly by the Fund; 109,661 shares held by the RA Capital Nexus Fund, L.P.; 28,569 shares held in a separately managed account; and pre-funded warrants exercisable for up to 8,178,412 shares held by the Fund. The filing notes that the pre-funded warrants contain a Beneficial Ownership Blocker capping the Fund's total ownership at 9.99%, and that the Fund "is currently prohibited from exercising the Pre-Funded Warrants by virtue of the Beneficial Ownership Blocker."

The filing further discloses that each of the Fund and the Nexus Fund has delegated to RA Capital the sole power to vote and dispose of all securities held in their portfolios, and that this delegation may not be revoked on less than 61 days' notice. As a result, each of the Fund and the Nexus Fund disclaims beneficial ownership for purposes of Section 13(d). Dr. Kolchinsky and Mr. Shah, as controlling persons of RA Capital Management GP, LLC, are identified as managers of RA Capital and may be deemed beneficial owners of the reported securities, though each similarly disclaims beneficial ownership other than for purposes of determining obligations under Section 13(d).

What Was Disclosed

RA Capital Management and affiliated reporting persons filed Amendment No. 14 to their Schedule 13D to report that their aggregate beneficial ownership in Solid Biosciences Inc. stands at 12,036,126 shares, or 10.8%, following dilution rather than any securities transaction.