OrbiMed Advisors Reports Passive Dilution in Q32 Bio Inc. Stake to 13.3%

On May 6, 2026, OrbiMed Advisors LLC and OrbiMed Capital GP VII LLC filed Amendment No. 2 to their Schedule 13D regarding Q32 Bio Inc. (QTTB). The reporting persons currently hold 2,252,987 shares of common stock, representing a 13.3% ownership stake based on 16,956,415 shares outstanding as of May 5, 2026. This filing reports a decrease in beneficial ownership percentage of more than 1% since the previous filing. This reduction was not caused by a sale of shares by the reporting persons, but rather resulted from an increase in the issuer's total outstanding shares. The shares are held directly by OrbiMed Private Investments VII, LP, with OrbiMed Advisors and OrbiMed GP sharing voting and dispositive power. Additionally, Diyong Xu, an employee of OrbiMed Advisors, serves on the issuer's Board of Directors. The reporting persons maintain a registration rights agreement covering these shares, originally established during the merger with Homology Medicines, Inc. in March 2024.