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): March 10, 2021

BAIN CAPITAL SPECIALTY FINANCE, INC.

(Exact name of Registrant as Specified in Its Charter)

Registrant’s telephone number, including area code: (617) 516-2000

N/A

(Former Name or Former Address, if Changed Since Last Report)

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:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company   ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Securities registered pursuant to Section 12(b) of the Act:

On March 10, 2021, Bain Capital Specialty Finance, Inc. (the “Company”) and U.S. Bank National Association (the “Trustee”), entered into an Indenture (the “Base Indenture”) and First Supplemental Indenture (the “First Supplemental Indenture,” and together with the Base Indenture, the “Indenture”) between the Company and the Trustee. The First Supplemental Indenture relates to the Company’s issuance of $300,000,000 aggregate principal amount of its 2.950% notes due 2026 (CUSIP 05684BAB3/ISIN US05684BAB36) (the “Notes”).

The Notes will mature on March 10, 2026 and may be redeemed in whole or in part at the Company’s option at any time or from time to time at the redemption prices set forth in the Indenture. The Notes bear interest at a rate of 2.950% per year payable semi-annually on March 10th and September 10th of each year, commencing on September 10, 2021. The Notes are general unsecured obligations of the Company that rank senior in right of payment to all of the Company’s existing and future indebtedness that is expressly subordinated in right of payment to the Notes, rank pari passu with all existing and future unsecured unsubordinated indebtedness issued by the Company, rank effectively junior to any of the Company’s secured indebtedness (including unsecured indebtedness that the Company later secures) to the extent of the value of the assets securing such indebtedness, and rank structurally junior to all existing and future indebtedness (including trade payables) incurred by the Company’s subsidiaries, financing vehicles or similar facilities.

The Indenture contains certain covenants, including covenants requiring the Company to comply with the asset coverage requirements of Section 18(a)(1)(A) as modified by Section 61(a)(1) and (2) of the Investment Company Act of 1940, as amended, whether or not it is subject to those requirements, and to provide financial information to the holders of the Notes and the Trustee if the Company is no longer subject to the reporting requirements under the Securities Exchange Act of 1934, as amended. These covenants are subject to important limitations and exceptions that are described in the Indenture.

In addition, on the occurrence of a “change of control repurchase event,” as defined in the Indenture, the Company will generally be required to make an offer to repurchase the outstanding Notes at a price equal to 100% of the principal amount of such Notes plus accrued and unpaid interest to the repurchase date.

The Notes were offered and sold in an offering registered under the Securities Act of 1933, as amended, pursuant to the Registration Statement on Form N-2 (File No. 333-250965) (the “Registration Statement”), the prospectus supplement dated March 4, 2021 and the pricing term sheet filed with the U.S. Securities and Exchange Commission on March 4, 2021. The transaction closed on March 10, 2021. The net proceeds to the Company were approximately $$294.5 million, after deducting the underwriting discounts and commissions of approximately $2.0 million payable by the Company and estimated offering expenses of approximately $1.1 million payable by the Company. The Company intends to use the net proceeds to repay outstanding indebtedness under its financing arrangements.

The foregoing descriptions of the First Supplemental Indenture and the Notes do not purport to be complete and are qualified in their entirety by reference to the full text of the First Supplemental Indenture and the Notes, respectively, each filed as exhibits hereto and incorporated by reference herein.

The information required by Item 2.03 contained in Item 1.01 of this Current Report on Form 8-K is incorporated herein by reference.

(d) Exhibits

SIGNATURES

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