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, 2019 Commission File Number: 001-36257 RETROPHIN, INC. (Exact Name of Registrant as specified in its Charter) Delaware 27-4842691 (State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.) 3721 Valley Centre Drive, Suite 200 San Diego, CA 92130 (Address of Princi ...