UNITED STATES SECURITIES AND EXCHANGE COMMISSION FORM 10-K For the fiscal year ended December 31, 2019 Unum Group (Mark One) WASHINGTON, D. C. 20549 ☒ Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 ☐ 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 001-11294 (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 1 Fountain Square Chattanooga, Tennessee (Address of principal executive offices) 62-1598430 (I.R.S. Employer Identification No.) 37402 (Zip Code) (423)294-1011 (Registrant's telephone number, including area code) Securities registered pursuant to Section 12(b) of the Act: Securities registered pursuant to Section 12(g) of the Act: None Indicate by check mark if the registrant is a well-known seasoned issuer as defined in Rule 405 of the Securities Act. Yes [X] No [ ] Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes [ ] No [X] Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes [X] No [ ] Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes [X] No [ ] Title of each class Trading Symbol Name of each exchange on which registered Common stock, $0.10 par value UNM New York Stock Exchange 6.250% Junior Subordinated Notes due 2058 UNMA New York Stock Exchange