FOR THE FISCAL YEAR ENDED DECEMBER 31, 2021 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: 001-38347 _____________________________________________________________________________________ Nine Energy Service, Inc. UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ______________________________________________________________________________________ FORM 10-K _________________________ ...