BVF Affiliates Report 4.3% Stake in Compass Therapeutics, Inc. (CMPX) via Schedule 13G/A

On May 15, 2026, Biotechnology Value Fund, L.P. (BVF) and its affiliates, including Mark N. Lampert, filed a Schedule 13G/A regarding their holdings in Compass Therapeutics, Inc. (CMPX). As of the event date on March 31, 2026, the reporting group collectively beneficially owns 7,764,842 shares of common stock, representing approximately 4.3% of the 180,087,915 shares outstanding. The aggregate ownership is distributed across several entities managed by BVF Partners L.P., including BVF (4,142,020 shares), Biotechnology Value Fund II, L.P. (3,028,951 shares), and Biotechnology Value Trading Fund OS LP (476,311 shares), plus 117,560 shares held in a managed account. This filing serves as an amendment to a previous disclosure. Mark N. Lampert, as a director and officer of BVF Inc., is deemed to have shared voting and dispositive power over the total aggregate shares. The filing indicates that the securities were not acquired for the purpose of changing or influencing the control of the issuer.