RA Capital Management Reports New 9.8% Stake in Q32 Bio Inc. Following Private Placement

On June 4, 2026, RA Capital Management, L.P., along with Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P., filed a Schedule 13G disclosing a new 9.8% ownership stake in Q32 Bio Inc. (QTTB). The reporting persons collectively beneficially own 2,332,457 shares of common stock. This position was established following a private placement of equity securities by the issuer that closed on May 28, 2026. RA Capital Management, L.P. serves as the investment adviser to the Fund and shares voting and dispositive power over the reported shares with Dr. Kolchinsky and Mr. Shah, who are the controlling persons of the firm. The calculation of the 9.8% ownership is based on a total of 23,681,415 shares outstanding, which includes 16,956,415 shares reported as of May 1, 2026, and the 6,725,000 shares issued in the recent private placement. The filing was made under Rule 13d-1(c), indicating a passive investment intent without the purpose of influencing or changing control of the issuer.