BlackRock, Inc. Reports New 6.8% Stake in SELLAS Life Sciences Group Inc.

On April 24, 2026, BlackRock, Inc. filed a Schedule 13G/A with the SEC, reporting a significant new ownership stake in SELLAS Life Sciences Group Inc. (SLS). As of the event date on March 31, 2026, BlackRock beneficially owns 12,136,331 shares of common stock, representing a 6.8% ownership interest in the company. This filing marks an increase from a previously reported 0.0% position, indicating a substantial new investment by the institutional holder. The filing specifies that BlackRock holds sole voting power over 11,966,938 shares and sole dispositive power over the full 12,136,331 shares. The securities were acquired in the ordinary course of business and are not held for the purpose of influencing or changing the control of the issuer. BlackRock filed this as a parent holding company on behalf of various subsidiaries listed in the exhibits. No individual person's interest within the reported holdings exceeds 5% of the total outstanding common shares of SELLAS Life Sciences.