Table of Contents Index to Financial Statements 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, 2018 ¨ 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 001-32336 (Digital Realty Trust, Inc.) 000-54023 (Digital Realty Trust, L.P.) DIGITAL REALTY TRUST, I ...