BlackRock, Inc. filed Amendment No. 2 to a Schedule 13G with the SEC on October 27, 2026, disclosing beneficial ownership of 15,872,685 shares of common stock in SELLAS Life Sciences Group Inc. as of September 30, 2026.

Key Highlights

  • Aggregate beneficial ownership: BlackRock reported beneficial ownership of 15,872,685 shares of SELLAS Life Sciences Group Inc. common stock.
  • Percent of class: The reported position represents 7.9% of the outstanding common shares, according to the filing.
  • Sole voting power: BlackRock disclosed sole voting power over 15,499,019 shares.
  • Sole dispositive power: BlackRock disclosed sole dispositive power over 15,872,685 shares.
  • No shared voting or dispositive power: Both shared voting power and shared dispositive power are reported as 0.
  • Event date: The date of event requiring this filing was September 30, 2026.

BlackRock's Amended Beneficial Ownership Position in SELLAS Life Sciences

According to the filing, BlackRock, Inc., organized in Delaware and headquartered at 50 Hudson Yards, New York, NY 10001, filed Amendment No. 2 to Schedule 13G disclosing its beneficial ownership in SELLAS Life Sciences Group Inc. (CUSIP 81642T209), whose principal executive offices are located at 7 Times Square, Suite 2503, New York, NY 10036. The filing was signed by Spencer Fleming, Managing Director, on October 27, 2026, and covers holdings as of the event date of September 30, 2026.

The filing states that BlackRock holds an aggregate of 15,872,685 shares beneficially owned, representing 7.9% of the class. Of those shares, the filing reports sole voting power over 15,499,019 shares and sole dispositive power over the full 15,872,685 shares. Shared voting and shared dispositive power are each reported as 0. The filing notes that the Schedule 13G reflects securities beneficially owned by certain business units of BlackRock, Inc. and its subsidiaries and affiliates, described collectively as the "Reporting Business Units," consistent with SEC Release No. 34-39538.

The filing further discloses, under Item 6, that "various persons have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of the common stock of SELLAS Life Sciences Group Inc." and that no single person's interest exceeds five percent of total outstanding common shares. BlackRock is classified as a parent holding company (type "HC") in the filing, and the relevant subsidiary information is included in Exhibit 99 as referenced under Item 7.

What Was Disclosed

BlackRock, Inc. filed an amended Schedule 13G reporting beneficial ownership of 15,872,685 shares, or 7.9%, of SELLAS Life Sciences Group Inc. common stock as of September 30, 2026, with sole voting power over 15,499,019 shares and sole dispositive power over all reported shares.