UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the fiscal year ended December 31, 2023 or ☐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 Incorpor ...