Brendan R. Winslow, Chief Financial Officer of Atrium Therapeutics, Inc., filed a statement of changes in beneficial ownership on September 22, 2026, reporting a transaction dated September 18, 2026, involving the withholding of common shares to cover tax obligations tied to vesting restricted stock units.

Key Highlights

  • Reporting person: Brendan R. Winslow, Chief Financial Officer of Atrium Therapeutics, Inc.
  • Transaction date: September 18, 2026, with the filing signed and dated September 22, 2026.
  • Shares withheld: 6,742 shares of Common Stock disposed of (transaction code F) at a price of $8.95 per share.
  • Purpose of withholding: According to the filing, the shares were withheld by the issuer to satisfy tax withholding obligations in connection with the vesting of restricted stock units.
  • Resulting ownership: Following the transaction, Winslow directly beneficially owned 36,859 shares of Common Stock.
  • Exchange and ticker: Atrium Therapeutics, Inc. is listed under the ticker symbol RNA, as stated in the filing's issuer field (NASDAQ:RNA).

Atrium Therapeutics CFO Beneficial Ownership Following RSU Vesting Transaction

According to the filing, Brendan R. Winslow, serving as Chief Financial Officer of Atrium Therapeutics, Inc., reported a single non-derivative securities transaction on September 18, 2026. The transaction involved 6,742 shares of Common Stock disposed of under transaction code F at a stated price of $8.95 per share. The filing's footnote explains that these shares were withheld directly by the issuer, not sold on the open market, specifically to satisfy tax withholding obligations arising from the vesting of restricted stock units.

Atrium Therapeutics, Inc., a biopharmaceutical company based in San Diego, California, is the issuer identified in the filing. Following the reported share withholding, Winslow's direct beneficial ownership of Atrium Therapeutics Common Stock stood at 36,859 shares, as disclosed in Table I of the filing. No derivative securities transactions were reported in Table II. The filing was made by one reporting person and is not an amendment to a prior filing.

What Was Disclosed

The filing disclosed that Atrium Therapeutics CFO Brendan R. Winslow had 6,742 shares of Common Stock withheld by the issuer at $8.95 per share on September 18, 2026, to cover tax obligations connected to RSU vesting, leaving him with direct beneficial ownership of 36,859 shares.