Bain Capital Life Sciences Entities Acquire Significant Stake in X4 Pharmaceuticals

Bain Capital Life Sciences Fund, L.P., Bain Capital Life Sciences Fund II, L.P., BCIP Life Sciences Associates, LP, BCLS II Investco, LP, and BCLS I Investco, LP (collectively, the "Reporting Persons") have filed a Schedule 13D to report their acquisition of a significant stake in X4 Pharmaceuticals, Inc. The Reporting Persons collectively beneficially own 9.99% of the outstanding Common Stock of X4 Pharmaceuticals, representing 2,436,526 shares as of August 13, 2025. This acquisition was made through the August 2025 Financing, where the Reporting Persons purchased shares and pre-funded warrants. Concurrently, X4 Pharmaceuticals' board of directors approved significant leadership changes, including the termination of the CEO and CFO, and the appointment of new executives. The Reporting Persons have entered into various agreements, including pre-funded warrants, warrants, and Class C warrants, which are subject to certain exercise blockers to prevent the Reporting Persons from exceeding beneficial ownership thresholds. The Reporting Persons have also entered into registration rights agreements with X4 Pharmaceuticals to facilitate the resale of their shares.