UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (cid:0) QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period e nded September 30, 2023 OR (cid:0) TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ___________ to___________ Commission File Number 000-14656 REPLIGEN CORPORATION (Exact Name of Registrant as Specified in its Charter) Delaware 04-27293 ...