OR UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019 ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) SECURITIES EXCHANGE ACT OF 1934 (Address of principal executive offices) (Zip Code) (312) 496-1200 Commission File No. 0-25837 HEIDRICK & STRUGGLES INTERNATIONAL, INC. (Exact Name of Registrant as Specified in its Charter) (State or Other Juris ...