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The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F3","text":"Of the shares of common stock reported,  193,254 shares represent restricted stock units."}],"balance_after":265305,"source":{"system":"sec-edgar","filing":"0001501697-26-000070","document":"wk-form4_1786651978.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1501697/000150169726000070/wk-form4_1786651978.xml","form_type":"4"}},{"id":1010454,"issuer":{"id":5638,"kind":"organization","name":"X4 Pharmaceuticals, Inc","symbol":"XFOR"},"owners":[{"id":23643,"kind":"person","name":"Volpone John","position":1,"cik":"0002081729","reported_name":"Volpone John","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President"}}],"security":"Stock Option (right to buy)","published_at":"2025-10-31T20:41:59.000Z","date":"2025-10-29","kind":"grant","planned":false,"acquired":true,"shares":2329154,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Represents stock options granted to the Reporting Person on August 12, 2025, which were subject to a performance-based vesting condition that was satisfied on October 29, 2025. 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