BVF Partners and Mark Lampert Report 5.4% Stake in Annexon, Inc. Following Warrant Exercise

On May 15, 2026, Biotechnology Value Fund, L.P. (BVF) and its affiliated reporting persons, including Mark N. Lampert, filed a Schedule 13G/A regarding their holdings in Annexon, Inc. (ANNX). As of March 31, 2026, the reporting group collectively beneficially owns 8,698,173 shares of Common Stock, representing approximately 5.4% of the company. This aggregate total includes 4,644,823 shares held by BVF, 3,399,850 shares held by BVF2, and 522,906 shares held by Trading Fund OS, plus 130,594 shares in a managed account. The filing notes that on March 27, 2026, the reporting persons exercised pre-funded warrants for 2,027,384 shares. BVF Partners L.P. serves as the investment manager for the funds, while Mark N. Lampert maintains ultimate shared voting and dispositive power. The reporting persons certified that the shares were acquired in the ordinary course of business and not for the purpose of changing or influencing the control of the issuer.