Washington, D.C. 20549 FORM 10-Q ý QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2019 or ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission file number: 001-31465 NATURAL RESOURCE PARTNERS L.P. UNITED STATES SECURITIES AND EXCHANGE COMMISSION (Exact name of registrant as specified in its charter) Delaware 35-2164875 (State or other jurisdiction of incorporation or organiz ...