X4 Pharmaceuticals, Inc

Departure of President, Chief Executive Officer and Principal Executive Officer

On August 11, 2025, Paula Ragan, Ph.D. notified the Company’s board of directors (the “Board”) of her resignation as President, Chief Executive Officer and principal executive officer of the Company and a member of the Board, in each case, effective as of 7 a.m. Eastern Standard Time on August 12, 2025 (the “Effective Time”) (the “CEO Separation”). Dr. Ragan’s resignation is not a result of any disagreement with the Company or any matter relating to financial policies or procedures. The Company anticipates entering into a separation agreement with Dr. Ragan (the “CEO Separation Agreement”), which shall provide that, subject to the Company’s receipt of a general release of claims against the Company, Dr. Ragan will receive (i) a one-time payment equal to 15 months of her current base salary, (ii) a one-time payment equal to approximately 87% of her target bonus for 2025, (iii) a monthly cash payment equal to the monthly employer contribution that the Company would have made to provide health insurance to her if she had remained employed by the Company until the earlier of 12 months following her last date of employment or the date she becomes eligible for health benefits through another employer or otherwise becomes ineligible for COBRA, and (iv) accelerated vesting of any currently unvested stock options and other stock-based awards currently held by Dr. Ragan.

The foregoing description of the CEO Separation Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the CEO Separation Agreement, a copy of which the Company intends to file as an exhibit to a future report under the Exchange Act after the execution of the CEO Separation Agreement.

Departure of Chief Financial Officer, Treasurer, Secretary and Principal Financial Officer

On August 11, 2025, Adam S. Mostafa notified the Board of his resignation as Chief Financial Officer, Treasurer, Secretary and principal financial officer of the Company, in each case, effective as of the Effective Time (the “CFO Separation”). The Company anticipates entering into a separation agreement with Mr. Mostafa (the “CFO Separation Agreement”), which shall provide that, subject to the Company’s receipt of a general release of claims against the Company, Mr. Mostafa will receive (i) a one-time payment equal to 12 months of his current base salary, (ii) a one-time payment equal to his target bonus for 2025, prorated through his last date of employment, (iii) a one-time cash payment equal to the monthly employer contribution that the Company would have made to provide health insurance to him if he had remained employed by the Company for six months, and (iv) accelerated vesting of any currently unvested stock options and other stock-based awards currently held by Mr. Mostafa.

The foregoing description of the CFO Separation Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the CFO Separation Agreement, a copy of which the Company intends to file as an exhibit to a future report under the Exchange Act after the execution of the CFO Separation Agreement.