UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 26, 2017

TPG Specialty Lending, Inc.

(Exact name of registrant as specified in charter)

Registrant’s telephone number, including area code: (817) 871-4000

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2 below):

Item 7.01 – Regulation FD Disclosure

On January 26, 2017, TPG Specialty Lending, Inc. (the “Company”) announced that it plans to conduct a private offering (the “Offering”) of $100 million aggregate principal amount of its Convertible Senior Notes due 2022 (the “Convertible Senior Notes”). The Company also plans to grant the initial purchasers an option to purchase up to an additional $15 million principal amount of the Convertible Senior Notes to cover over-allotments, if any. In connection with the Offering, the Company intends to disclose certain information to potential investors, some of which has not been previously reported.

The Company estimates that the net proceeds it will receive from the sale of the $100 million aggregate principal amount of notes in the Offering will be approximately $96.0 million (or approximately $110.6 million if the initial purchasers fully exercise their over-allotment option), in each case after deducting the discounts and commissions and estimated offering expenses payable by the Company.

The Company intends to use 100% of the net proceeds of the Offering to pay down a portion of the outstanding indebtedness on its second amended and restated senior secured revolving credit facility, dated February 27, 2014 (as amended, the “Revolving Credit Facility”) on or about the date of the closing of the Offering. As of January 20, 2017, the Company had $625.0 million outstanding under the Revolving Credit Facility. However, through reborrowing under the Revolving Credit Facility, the Company intends to make new investments in accordance with its investment objective and strategies. As of September 30, 2016, amounts outstanding under the Revolving Credit Facility bore interest at a rate of LIBOR plus 200 basis points. For $885.0 million of the commitments under the Revolving Credit Facility, the maturity date is December 22, 2021 and for the remaining $60.0 million, the maturity date is October 2, 2020.

In connection with the Offering, the Company intends to enter into interest rate swaps to better align the interest rates of its liabilities with its investment portfolio, which consists of predominately floating rate loans.

In addition, on January 26, 2017, the Company issued a press release announcing that it plans to conduct the Offering. A copy of the press release is filed herewith as Exhibit 99.1 and incorporated herein by reference.

Neither the Convertible Senior Notes nor the common stock that may be issued upon conversion thereof will be registered under the Securities Act of 1933 (as amended, the “Securities Act”). Neither the Convertible Senior Notes nor the common stock that may be issued upon conversion thereof may be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Securities Act.

The information disclosed under this Item 7.01, including Exhibit 99.1 hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and shall not be deemed incorporated by reference into any filing made under the Securities Act, except as expressly set forth by specific reference in this filing or in any other such filing. The furnishing of this information pursuant to Item 7.01 shall not be deemed an admission by the Company as to the materiality of such information.

Item 9.01 – Financial Statements and Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.