Atlas Venture Affiliates Increase Stake in Q32 Bio Inc. via $5M PIPE Investment

On May 28, 2026, Atlas Venture Fund X, L.P. and its affiliated entities (the "Reporting Persons") filed an amendment to their Schedule 13D regarding Q32 Bio Inc. (QTTB). This filing reports a significant increase in holdings following the closure of a private placement (the "2026 PIPE") on May 28, 2026. Specifically, Atlas Venture Opportunity Fund III, L.P. (AVOF III) purchased 625,000 shares of common stock at $8.00 per share, totaling a $5 million investment. Collectively, the Reporting Persons now beneficially own 2,717,106 shares, representing approximately 11.5% of the 23,681,415 shares outstanding. Individually, Atlas Venture Fund X holds 864,261 shares (3.6%), AVOF holds 503,296 shares (2.1%), AVOF II holds 724,549 shares (3.1%), and AVOF III holds 625,000 shares (2.6%). In connection with the 2026 PIPE, the Issuer entered into a Registration Rights Agreement requiring a resale registration statement to be filed within 50 days. The Reporting Persons are under common control but disclaim membership in a formal group.