Form 8-K

8-K — Sixth Street Specialty Lending, Inc.

Accession: 0001193125-26-206354

Filed: 2026-05-05

Period: 2026-05-05

CIK: 0001508655

Item: Results of Operations and Financial Condition

Item: Regulation FD Disclosure

Item: Financial Statements and Exhibits

Documents

8-K — tslx-20260505.htm (Primary)

EX-99.1 (tslx-ex99_1.htm)

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XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K

8-K (Primary)

Filename: tslx-20260505.htm · Sequence: 1

8-K

false000150865500015086552026-05-052026-05-05

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): May 5, 2026

Sixth Street Specialty Lending, Inc.

(Exact name of registrant as specified in charter)

Delaware

001-36364

27-3380000

(State or Other Jurisdiction

of Incorporation)

(Commission

File Number)

(I.R.S. Employer

Identification No.)

2100 McKinney Avenue, Suite 1500

Dallas, TX

75201

(Address of Principal Executive Offices)

(zip code)

Registrant’s telephone number, including area code: (469) 621-3001

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):

☐

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.01 per share

TSLX

The New York Stock Exchange

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. ☐

Item 2.02 – Results of Operations and Financial Condition

On May 5, 2026, Sixth Street Specialty Lending, Inc. (the “Company”) issued a press release announcing its financial results for the three months ended March 31, 2026. The text of the press release is included as Exhibit 99.1 to this Form 8-K.

The information disclosed under this Item 2.02, 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 and shall not be deemed incorporated by reference into any filing made under the Securities Act of 1933, except as expressly set forth by specific reference in such filing.

Item 7.01 – Regulation FD Disclosure

On May 5, 2026, the Company issued a press release, included herewith as Exhibit 99.1, announcing the declaration of a second quarter 2026 base dividend per share of $0.42 to shareholders of record as of June 15, 2026, payable on June 30, 2026.

The Company announced today that Michael Fishman has been appointed to serve as Chairman of the Company’s Board of Directors, effective as of the close of business on May 21, 2026.

Michael Fishman was elected a director of the Company in April 2011. From April 2011 to December 2013, he served as Chief Executive Officer, and from December 2013 to December 2017, he served as Co-Chief Executive Officer with Joshua Easterly. Mr. Fishman is a Vice President of the Company and is a Sixth Street Partner. He has been an executive in corporate lending for more than 30 years with senior management experience in credit, portfolio management and primary loan originations. Prior to joining Sixth Street, Mr. Fishman was the Executive Vice President and National Director of Loan Originations for WFCF, formerly known as Wells Fargo Foothill and Foothill Capital Corporation. Fishman has also contributed to various industry publications and panel discussions, and has sat on the Board of the American Bankruptcy Institute. He holds a Bachelor of Science in Finance from Rochester Institute of Technology.

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, and shall not be deemed incorporated by reference into any filing made under the Securities Act of 1933, except as expressly set forth by specific reference in such filing.

Item 9.01 – Financial Statements and Exhibits

(d) Exhibits:

Exhibit

Number

Description

99.1

Press Release, dated May 5, 2026

104

The cover page of this Current Report on Form 8-K, formatted in Inline XBRL

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.

SIXTH STREET SPECIALTY LENDING, INC.

(Registrant)

Date: May 5, 2026

By:

/s/ Ian Simmonds

Ian Simmonds

Chief Financial Officer

EX-99.1

Filename: tslx-ex99_1.htm · Sequence: 2

EX-99.1

Exhibit 99.1

FIRST QUARTER 2026 EARNINGS RESULTS

Sixth Street Specialty Lending, Inc. Reports First Quarter Results; Declares a Second Quarter Base Dividend Per Share of $0.42

NEW YORK — May 5, 2026 — Sixth Street Specialty Lending, Inc. (NYSE: TSLX, or the “Company”) today reported net investment income of $0.42 per share and net loss of $0.27 per share for the first quarter ended March 31, 2026. These results correspond to an annualized return on equity (ROE) on net investment income and net income of 9.9% and -6.5%, respectively. Reported and adjusted metrics converged this quarter, as there was no impact related to capital gains incentive fees.

Reported net asset value (NAV) per share was $16.24 at March 31, 2026 as compared to NAV per share of $16.98 or an adjusted NAV per share of $16.97 at December 31, 2025 (which accounts for the impact of the $0.01 per share fourth quarter 2025 supplemental dividend). The main driver of this quarter’s NAV per share decline was $0.58 per share attributable to movement in fair value from market inputs. This included $0.40 per share from unrealized losses in the debt portfolio tied to credit spread widening seen in the broader market and $0.18 per share from lower market valuations in the Company’s limited equity portfolio.

The Company announced that its Board of Directors has declared a second quarter 2026 base dividend of $0.42 per share to shareholders of record as of June 15, 2026, payable on June 30, 2026. The decision to revise the base dividend level was informed by what the Company believes is a responsible and sustainable dividend policy. The supplemental dividend policy remains in place to distribute over-earning to shareholders based on the existing framework.

On May 1, 2026, the Company completed an amendment to its Revolving Credit Facility, which extended the stated maturity date to May 1, 2031 for $1.525 billion of commitments. The pricing and other material terms of the facility remain unchanged.

Net Investment Income Per Share

Q1 2026:

$0.42

Net Loss Per Share

Q1 2026:

$0.27

Return on Equity

Q1 2026 (NII):

9.9%

Q1 2026 (NI):

(6.5)%

NAV

Q1 2026 ($MM):

$1,542.7

Q1 2026 (per share):

$16.24

Dividends Declared (per share)

Q1 2026 (Base):

$0.46

LTM Q1 2026 (Base):

$1.84

LTM Q1 2026 (Supplemental):

$0.15

LTM Q1 2026 (Total):

$1.99

Portfolio and Investment Activity

For the quarter ended March 31, 2026, new investment commitments totaled $338.1 million. This compares to $242.4 million for the quarter ended December 31, 2025.

For the quarter ended March 31, 2026, the principal amount of new investments funded was $134.8 million across two new portfolio companies, four upsizes to existing portfolio companies and an initial investment in the previously announced joint venture, Structured Credit Partners. For this period, the Company had $113.0 million aggregate principal amount in exits and repayments. For the quarter ended December 31, 2025, the principal amount of new investments funded was

$196.7 million across five new portfolio companies and four upsizes to existing portfolio companies. For this period, the Company had $234.9 million aggregate principal amount in exits and repayments.

The Company had investments in 1431 portfolio companies as of March 31, 2026 and December 31, 2025 with an aggregate fair value of $3,313.4 million and $3,347.3 million, respectively. As of March 31, 2026, the average investment size in each portfolio company was $30.1 million based on fair value.

As of March 31, 2026, the Company’s portfolio based on fair value consisted of 89.3% first-lien debt investments, 1.0% second-lien debt investments, 1.9% mezzanine debt investments, 4.6% equity investments, 2.8% structured credit investments and 0.4% joint venture investments. As of December 31, 2025, the Company’s portfolio based on fair value consisted of 89.2% first-lien debt investments, 0.9% second-lien debt investments, 1.8% mezzanine debt investments, 5.2% equity and other investments and 2.9% structured credit investments.

As of March 31, 2026, 96.3% of debt investments2 based on fair value in the portfolio bore interest at floating rates with 100.0% of these subject to reference rate floors. The Company’s credit facilities also bear interest at floating rates. In connection with the Company’s Unsecured Notes, which bear interest at fixed rates, the Company has entered into fixed-to-floating interest rate swaps in order to align the nature of the interest rates of its liabilities with its investment portfolio.

As of March 31, 2026 and December 31, 2025, the weighted average total yield of debt and income-producing securities at fair value (which includes interest income and amortization of fees and discounts) was 11.1% and 11.1%, respectively, and the weighted average total yield of debt and income-producing securities at amortized cost (which includes interest income and amortization of fees and discounts) was 11.2% and 11.3% for the quarter ended March 31, 2026 and December 31, 2025, respectively.

As of March 31, 2026 and December 31, 2025, 1.4% and 0.6% of the portfolio at fair value was on non-accrual status, respectively. There was one addition and one removal from non-accrual status during the quarter, resulting in no change to the total number of investments on non-accrual at three names.

Q1 2026 Origination Activity

Commitments:

$338.1MM

Fundings:

$134.8MM

Net Fundings:

$21.8MM

Average Investment Size

$30.1MM

(0.9% of the portfolio at fair value)

First Lien Debt Investments (% FV)

89.3%

Floating Rate Debt Investments2

(% FV)

96.3%

Weighted Average Yield of Debt and Incoming-Producing Securities

Yield at Fair Value:

11.1%

Yield at Amortized Cost:

11.2%

Includes 36 structured credit investments with a total fair value as of March 31, 2026 and December 31, 2025 of $93.8 million and $97.9 million, respectively.

Calculation includes income earning debt investments only.

RESULTS OF OPERATIONS FOR THE THREE MONTHS ENDED march 31, 2026

Total Investment Income

For the three months ended March 31, 2026 and 2025, investment income was $93.4 million and $116.3 million, respectively. The decrease in investment income was primarily the result of a decrease in reference rates for the three months ended March 31, 2026 compared to the same period in 2025.

$93.4MM

Net Expenses

Net expenses totaled $52.4 million and $57.0 million for the three months ended March 31, 2026 and 2025, respectively. The decrease in net expenses was primarily due to a decrease in the average interest rate on our debt outstanding, which decreased from 6.4% for the three months ended March 31, 2025 to 5.5% for the three months ended March 31, 2026 due to a change in the mix of our debt financing sources and a change in SOFR rates.

$52.4MM

Debt and Capital Resources

As of March 31, 2026, the Company had $29.2 million in cash and cash equivalents (including $28.1 million of restricted cash), total principal value of debt outstanding of $1,827.4 million, and $1,074.8 million of undrawn capacity on its revolving credit facility, subject to borrowing base and other limitations. The Company’s weighted average interest rate on debt outstanding was 5.5% and 6.0% for the three-month periods ended March 31, 2026 and December 31, 2025, respectively. At March 31, 2026, the Company’s debt to equity ratio was 1.18x, compared to 1.10x at December 31, 2025. Average debt to equity was 1.14x for the three-month period ended March 31, 2026, compared to 1.17x for the three-month period ended December 31, 2025.

Total Principal Debt Outstanding

$1,827.4MM

Debt-to-Equity Ratio

Q1 2026 Quarter End:

1.18x

Q1 2026 Average1:

1.14x

Daily average debt outstanding during the quarter divided by the average net assets during the quarter. Average net assets is calculated by starting with the prior quarter end net asset value and adjusting for capital activity during the quarter (adding common stock offerings / DRIP contributions).

LIQUIDITY AND FUNDING PROFILE

Liquidity

The following tables summarize the Company’s liquidity at March 31, 2026 and changes to unfunded commitments since December 31, 2025.

$ Millions

Revolving Credit Facility1

Unfunded Commitment Activity

Revolver Capacity

$1,525

Unfunded Commitments (See Note 8 in 12/31/25 10-K)

$339

Drawn on Revolver

($577)

Extinguished Unfunded Commitments

($7)

Unrestricted Cash Balance

New Unfunded Commitments

$220

Issued Letters of Credit

($23)

Net Drawdown of Unfunded Commitments

($39)

Total Liquidity (Pre-Unfunded Commitments)

$926

Total Unfunded Commitments

$512

Available Unfunded Commitments2

($249)

Unavailable Unfunded Commitments2

($263)

Total Liquidity (Burdened for Unfunded Commitments)

$701

Available Unfunded Commitments2

$249

Adjusted for 17th amendment and extension to the revolving credit facility closed on May 1, 2026. As part of the transaction, $150 million of remaining non-extending commitments with a maturity of April 23, 2027 and a revolving period ending April 24, 2026 were terminated.

Commitments may be subject to limitations on borrowings set forth in the agreements between the Company and the applicable portfolio company. As a result, portfolio companies may not be eligible to borrow the full commitment amount on such date.

Note: May not sum due to rounding.

Funding Profile

At March 31, 2026, the Company’s funding mix was comprised of approximately 68% unsecured and 32% secured debt. As illustrated below, the Company’s nearest debt maturity is in August 2026 at $300 million, and the weighted average remaining life of investments funded with debt was ~2.5 years, compared to a weighted average remaining maturity on debt of ~3.9 years1,2.

Weighted by gross commitment amount.

Note: Numbers may not sum due to rounding.

Conference Call and Webcast

Conference Call Information:

A conference call to discuss the Company’s financial results will be held at 8:30 a.m. Eastern Time on May 6, 2026. The conference call will be broadcast live in listen-only mode on the Investor Resources section of TSLX’s website at https://sixthstreetspecialtylending.gcs-web.com/events-and-presentations. The Events & Presentations page of the Investor Resources section of TSLX’s website also includes a slide presentation that complements the Earnings Conference Call. Please visit the website to test your connection before the webcast.

Research analysts who wish to participate in the conference call must first register at https://register-conf.media-server.com/register/BI661ff50b864d41c7a257bed82c561eae. Upon registration, all telephone participants will receive a confirmation email detailing how to join the conference call, including the dial-in number along with a unique passcode and registrant ID that can be used to access the call.

Replay Information:

A recorded version will be available under the same webcast link (https://sixthstreetspecialtylending.gcs-web.com/events-and-presentations) following the conclusion of the conference call.

Financial Highlights

(Amounts in millions, except per share amounts)

Three Months Ended

(unaudited)

March 31, 2026

December 31, 2025

March 31, 2025

Investments at Fair Value

3,313.4

3,347.3

3,412.0

Total Assets

3,393.1

3,421.7

3,498.5

Net Asset Value Per Share

16.24

16.98

17.04

Supplemental Dividend Per Share

0.00

0.01

0.06

Adjusted Net Asset Value Per Share (1)

16.24

16.97

16.98

Investment Income

93.4

108.2

116.3

Net Investment Income

39.8

50.4

58.0

Net Income (Loss)

(26.0

)

30.0

37.0

Accrued Capital Gains Incentive Fee Expense

0.0

(1.8

)

(3.7

)

Adjusted Net Investment Income (2)

39.8

48.6

54.3

Adjusted Net Income (Loss) (2)

(26.0

)

28.2

33.3

Net Investment Income Per Share

0.42

0.53

0.62

Net Income (Loss) Per Share

(0.27

)

0.32

0.39

Accrued Capital Gains Incentive Fee Expense Per Share

0.0

(0.01

)

(0.04

)

Adjusted Net Investment Income Per Share (2)

0.42

0.52

0.58

Adjusted Net Income (Loss) Per Share (2)

(0.27

)

0.30

0.36

Annualized Return on Equity (Net Investment Income) (3)

9.9

12.5

14.4

Annualized Return on Equity (Net Income (Loss)) (3)

(6.5)%

7.4

9.2

Annualized Return on Equity (Adjusted Net Investment Income) (2)(3)

9.9

12.0

13.5

Annualized Return on Equity (Adjusted Net Income (Loss)) (2)(3)

(6.5)%

7.0

8.3

Weighted Average Yield of Debt and Income Producing Securities at Fair Value

11.1

12.1

Weighted Average Yield of Debt and Income Producing Securities at Amortized Cost

11.2

11.3

12.3

Percentage of Debt Investment Commitments at Floating Rates

96.3

97.0

Adjusted net asset value per share gives effect to the supplemental dividend declared related to earnings or special dividend in the applicable period.

Adjusted to exclude the capital gains incentive fee that was accrued, but not paid, related to cumulative unrealized capital gains in excess of cumulative net realized capital gains less any cumulative unrealized losses and capital gains incentive fees paid inception to date.

Return on equity is calculated using prior period’s ending net asset value per share.

Financial Statements and Tables

Sixth Street Specialty Lending, Inc.

Consolidated Balance Sheets

(Amounts in thousands, except share and per share amounts)

March 31, 2026

December 31, 2025

Assets

Investments at fair value

Non-controlled, non-affiliated investments (amortized cost of $3,228,777 and $3,244,762, respectively)

3,240,271

3,288,945

Non-controlled, affiliated investments (amortized cost of $14,665, and $0, respectively)

14,665

—

Controlled, affiliated investments (amortized cost of $80,890 and $78,520, respectively)

58,505

58,372

Total investments at fair value (amortized cost of $3,324,332 and $3,323,282, respectively)

3,313,441

3,347,317

Cash and cash equivalents (restricted cash of $28,072 and $16,727, respectively)

29,178

19,662

Interest receivable

34,547

34,132

Prepaid expenses and other assets

15,983

20,544

Total Assets

3,393,149

3,421,655

Liabilities

Debt (net of deferred financing costs of $22,693 and $24,411, respectively)

1,803,391

1,743,234

Management fees payable to affiliate

12,275

12,794

Incentive fees on net investment income payable to affiliate

8,451

10,336

Incentive fees on net capital gains accrued to affiliate

—

Other payables to affiliate

2,808

3,166

Other liabilities

23,551

44,404

Total Liabilities

1,850,476

1,813,934

Commitments and contingencies (Note 8)

Net Assets

Preferred stock, $0.01 par value; 100,000,000 shares authorized; no shares

issued and outstanding

—

Common stock, $0.01 par value; 400,000,000 shares authorized, 95,683,850

and 95,369,400 shares issued, respectively; and 95,019,600 and 94,705,150

shares outstanding, respectively

957

954

Additional paid-in capital

1,541,068

1,535,583

Treasury stock at cost; 664,250 and 664,250 shares held, respectively

(10,459

)

(10,459

)

Distributable earnings

11,107

81,643

Total Net Assets

1,542,673

1,607,721

Total Liabilities and Net Assets

3,393,149

3,421,655

Net Asset Value Per Share

16.24

16.98

Sixth Street Specialty Lending, Inc.

Consolidated Statements of Operations

(Amounts in thousands, except share and per share amounts)

Three Months Ended

March 31, 2026

March 31, 2025

Income

Investment income from non-controlled, non-affiliated investments:

Interest from investments

81,807

104,192

Paid-in-kind interest income

6,969

5,360

Dividend income

237

908

Other income

2,181

3,459

Total investment income from non-controlled, non-affiliated investments

91,194

113,919

Investment income from non-controlled, affiliated investments:

Dividend income

223

—

Total investment income from non-controlled, affiliated investments

223

—

Investment income from controlled, affiliated investments:

Interest from investments

1,971

2,429

Other income

Total investment income from controlled, affiliated investments

1,980

2,430

Total Investment Income

93,397

116,349

Expenses

Interest

28,258

32,971

Management fees

12,593

13,083

Incentive fees on net investment income

8,451

11,516

Incentive fees on net capital gains

—

(3,686

)

Professional fees

1,743

1,961

Directors’ fees

254

248

Other general and administrative

1,369

1,337

Total expenses

52,668

57,430

Management and incentive fees waived (Note 3)

(317

)

(409

)

Net Expenses

52,351

57,021

Net Investment Income Before Income Taxes

41,046

59,328

Income taxes, including excise taxes

1,204

1,350

Net Investment Income

39,842

57,978

Unrealized and Realized Gains (Losses)

Net change in unrealized gains (losses):

Non-controlled, non-affiliated investments

(32,688

)

(9,438

)

Controlled, affiliated investments

(2,237

)

(1,379

)

Translation of other assets and liabilities in foreign currencies

8,401

(11,043

)

Total net change in unrealized gains (losses)

(26,524

)

(21,860

)

Realized gains (losses):

Non-controlled, non-affiliated investments

(39,257

)

1,115

Foreign currency transactions

(86

)

(278

)

Total net realized gains (losses)

(39,343

)

837

Total Net Unrealized and Realized Gains (Losses)

(65,867

)

(21,023

)

Increase (Decrease) in Net Assets Resulting from Operations

(26,025

)

36,955

Earnings per common share—basic and diluted

(0.27

)

0.39

Weighted average shares of common stock outstanding—basic and diluted

94,709,407

93,669,671

The Company’s investment activity for the quarter ended March 31, 2026 and 2026 presented below (information presented herein is at par value unless otherwise indicated).

Three Months Ended

($ in millions)

March 31, 2026

March 31, 2025

New investment commitments:

Gross originations (1)

1,879.3

1,254.9

Less: Syndications/sell downs (1)

1,541.2

1,100.5

Total new investment commitments

338.1

154.4

Principal amount of investments funded:

First-lien

120.1

102.2

Second-lien

—

18.9

Mezzanine

—

13.0

Equity

—

2.7

Structured Credit

—

Joint Venture

14.7

—

Total

134.8

136.8

Principal amount of investments sold or repaid:

First-lien

110.1

267.1

Second-lien

—

Mezzanine

—

Equity

2.9

1.0

Structured Credit

—

1.5

Joint Venture

—

Total

113.0

269.6

Number of new investment commitments in

new portfolio companies

Average new investment commitment amount in

new portfolio companies (2)

98.5

21.4

Weighted average term for new investment

commitments in new portfolio companies

(in years) (2)

6.3

5.2

Percentage of new debt investment commitments

at floating rates

100.0

85.1

Percentage of new debt investment commitments

at fixed rates

0.0

14.9

Weighted average interest rate of new

investment commitments

9.6

11.3

Weighted average spread over reference rate of new

floating rate investment commitments

6.1

7.0

Weighted average interest rate on investments

fully sold or paid down

10.4

11.8

Includes affiliates of Sixth Street.

For three months ended March 31, 2026, includes the joint venture investment commitment of $200.0 million which is excluded

from the calculation of weighted average term for new investment commitments in new portfolio companies.

About Sixth Street Specialty Lending

Sixth Street Specialty Lending is a specialty finance company focused on lending to middle-market companies. The Company seeks to generate current income primarily in U.S.-domiciled middle-market companies through direct originations of senior secured loans and, to a lesser extent, originations of mezzanine loans and investments in corporate bonds and equity securities. The Company has elected to be regulated as a business development company, or a BDC, under the Investment Company Act of 1940 and the rules and regulations promulgated thereunder. The Company is externally managed by Sixth Street Specialty Lending Advisers, LLC, an affiliate of Sixth Street and a Securities and Exchange Commission (“SEC”) registered investment adviser. The Company leverages the deep investment, sector, and operating resources of Sixth Street, a global investment firm with over $130 billion in assets under management and committed capital. For more information, visit the Company’s website at https://sixthstreetspecialtylending.com.

About Sixth Street

Sixth Street is a global investment firm with over $130 billion in assets under management and committed capital. The firm uses its long-term flexible capital, data-enabled capabilities, and One Team culture to develop themes and offer solutions to companies across all stages of growth. Founded in 2009, Sixth Street has more than 750 team members including over 300 investment professionals around the world. For more information, visit https://sixthstreet.com or follow Sixth Street on LinkedIn.

Forward-Looking Statements

Statements included herein may constitute “forward-looking statements,” within the meaning of the federal securities laws and the Private Securities Litigation Reform Act of 1995, which relate to future events or the Company’s future performance or financial condition. These forward-looking statements can be identified by the use of forward-looking terminology, such as “outlook,” “indicator,” “believes,” “expects,” “potential,” “continues,” “may,” “can,” “will,” “should,” “seeks,” “approximately,” “predicts,” “intends,” “plans,” “estimates,” “anticipates”, “confident,” “conviction,” “identified” or the negative versions of these words or other comparable words thereof. These statements are not guarantees of future performance, conditions or results and involve a number of risks and uncertainties. Actual results may differ materially from those in the forward-looking statements as a result of a number of factors, including those described from time to time in the Company’s filings with the SEC, which are accessible on the SEC’s website at www.sec.gov. Except as otherwise required by federal securities laws, the Company assumes no obligation to update any such forward-looking statements, whether as a result of new information, future developments or otherwise.

Non-GAAP Financial Measures

Adjusted net investment income and adjusted net income are each non-GAAP financial measures, which represent net investment income and net income, respectively, in each case less the impact of accrued capital gains incentive fee expenses. The Company believes that adjusted net investment income and adjusted net income provide useful information to investors regarding the fundamental earnings power of the business, and these figures are used by the Company to measure its financial condition and results of operations. The presentation of this additional information is not meant to be considered in isolation or as a substitute for financial results prepared in accordance with GAAP.

Investors:

Cami Senatore, 469-621-2033

Sixth Street Specialty Lending

IRTSLX@sixthstreet.com

Media:

Patrick Clifford, 617-793-2004

Sixth Street

PClifford@sixthstreet.com

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v3.26.1

Document and Entity Information

May 05, 2026

Cover [Abstract]

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false

Entity Central Index Key

0001508655

Document Type

8-K

Document Period End Date

May 05, 2026

Entity Registrant Name

Sixth Street Specialty Lending, Inc.

Entity Incorporation State Country Code

Entity File Number

001-36364

Entity Tax Identification Number

27-3380000

Entity Address, Address Line One

2100 McKinney Avenue

Entity Address, Address Line Two

Suite 1500

Entity Address, City or Town

Dallas

Entity Address, State or Province

Entity Address, Postal Zip Code

75201

City Area Code

(469)

Local Phone Number

621-3001

Written Communications

false

Soliciting Material

false

Pre Commencement Tender Offer

false

Pre Commencement Issuer Tender Offer

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Security 12b Title

Common Stock, par value $0.01 per share

Trading Symbol

TSLX

Security Exchange Name

NYSE

Entity Emerging Growth Company

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