UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q ☒ Quarterly report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2023 ☐ 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 001-33957 HARVARD BIOSCIENCE, INC. (Exact Name of Registrant as Specified in Its Charter) Delaware 04-3306140 (State or other jurisdiction of In ...