NEW YORK — November 4, 2025 — Sixth Street Specialty Lending, Inc. (NYSE: TSLX, or the “Company”) today reported net investment income of $0.54 per share and net income of $0.47 per share for the third quarter ended September 30, 2025. These results correspond to an annualized return on equity (ROE) on net investment income and net income of 12.5% and 11.0%, respectively.

Both net investment income per share and net income per share include $0.01 per share of unwind of previously accrued capital gains incentive fee expenses. Excluding the impact of the partial reversal or unwind of previously accrued capital gains incentive fee expenses, the Company’s adjusted net investment income and adjusted net income for the quarter ended September 30, 2025, were $0.53 per share and $0.46 per share, respectively. These results correspond to an annualized return on equity (ROE) on adjusted net investment income and adjusted net income of 12.3% and 10.8%, respectively.

Reported net asset value (NAV) per share was $17.14 at September 30, 2025 as compared to NAV per share of $17.17 or an adjusted NAV per share of $17.12 at June 30, 2025 (which accounts for the impact of the $0.05 per share second quarter 2025 supplemental dividend). The change in NAV per share was primarily driven by the reversal of net unrealized gains on the balance sheet related to investment realizations that were recognized in this quarter's net investment income.

The Company announced that its Board of Directors has declared a fourth quarter 2025 base dividend of $0.46 per share to shareholders of record as of December 15, 2025, payable on December 31, 2025, and a third quarter supplemental dividend of $0.03 per share to shareholders of record as of November 28, 2025, payable on December 19, 2025. Adjusted for the impact of the supplemental dividend related to this quarter’s earnings, the Company’s Q3 adjusted NAV per share was $17.11.

Net Investment Income Per Share

Q3 2025:

$0.54

Q3 2025 (adjusted):

$0.53

Net Income Per Share

Q3 2025:

$0.47

Q3 2025 (adjusted):

$0.46

Return on Equity

Q3 2025 (NII):

12.5%

Q3 2025 (NI):

11.0%

Q3 2025 (Adj. NII):

12.3%

Q3 2025 (Adj. NI):

10.8%

NAV

Q3 2025 ($MM):

$1,619.7

Q3 2025 (per share):

$17.14

Q3 2025 (per share, adj):

$17.11

Dividends Declared (per share)

Q3 2025 (Base):

$0.46

LTM Q3 2025 (Base):

$1.84

LTM Q3 2025 (Supplemental):

$0.21

LTM Q3 2025 (Total):

$2.05

For the quarter ended September 30, 2025, new investment commitments totaled $387.7 million. This compares to $297.7 million for the quarter ended June 30, 2025.

For the quarter ended September 30, 2025, the principal amount of new investments funded was $351.8 million across four new portfolio companies, five upsizes to existing portfolio companies and several structed credit investments. For this period, the Company had $302.8 million aggregate principal amount in exits and repayments. For the quarter ended June 30, 2025, the principal amount of new investments funded was $208.6 million across thirteen new portfolio companies (including structured credit investments) and four upsizes to existing portfolio companies. For this period, the Company had $388.7 million aggregate principal amount in exits and repayments.

As of September 30, 2025 and June 30, 2025, the Company had investments in 1451 and 109 portfolio companies, respectively, with an aggregate fair value of $3,376.3 million and $3,294.9 million, respectively. As of September 30, 2025, the average investment size in each portfolio company was $23.31 million based on fair value.

As of September 30, 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 investments and 2.9% structured credit investments. As of June 30, 2025, the Company’s portfolio based on fair value consisted of 92.4% first-lien debt investments, 0.9% second-lien debt investments, 1.6% mezzanine debt investments, and 5.1% equity investments.

As of September 30, 2025, 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 September 30, 2025 and June 30, 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 11.4% and 11.7%, 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 11.7% and 12.0% for the quarter ended September 30, 2025 and June 30, 2025, respectively.

As of September 30, 2025 and June 30, 2025, 0.6% of the portfolio at fair value was on non-accrual status. No new investments were added to non-accrual status during the third quarter.

Q3 2025 Origination Activity

Commitments:

$387.7MM

Fundings:

$351.8MM

Net Fundings:

$49.0MM

Average Investment Size1

$23.3MM

(0.7% of the portfolio at fair value)

First Lien Debt Investments (% FV)

89.2%

Floating Rate Debt Investments2

(% FV)

96.3%

Weighted Average Yield of Debt and Incoming-Producing Securities

Yield at Fair Value:

11.4%

Yield at Amortized Cost:

11.7%

1. As of September 30, 2025, includes 37 structured credit investments with a total fair value of $99.3 million. Excluding structured credit investments results in 108 portfolio companies with an average investment size of $30.3 million.

2. Calculation includes income earning debt investments only.

Total Investment Income

Total Investment Income

For the three months ended September 30, 2025 and 2024, investment income was $109.4 million and $119.2 million, respectively. The decrease in investment income was largely the result of lower interest rates, partially offset by higher activity-based fee income.

$109.4MM

Net Expenses

Net Expenses

Net expenses totaled $57.4 million and $63.6 million for the three months ended September 30, 2025 and 2024, respectively. The decrease in net expenses was primarily due to the downward movement in reference rates which decreased the Company’s weighted average interest rate on average debt outstanding.

$57.4MM

Debt and Capital Resources

As of September 30, 2025, the Company had $83.2 million in cash and cash equivalents (including $20.1 million of restricted cash), total principal value of debt outstanding of $1,858.7 million, and $1,046.6 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 6.3% for the three-month periods ended September 30, 2025 and June 30, 2025. At September 30, 2025, the Company’s debt to equity ratio was 1.15x, compared to 1.09x at June 30, 2025. Average debt to equity was 1.10x for the three-month period ended September 30, 2025, compared to 1.20x for the three-month period ended June 30, 2025.

Total Principal Debt Outstanding

$1,858.7MM

Debt-to-Equity Ratio

Q3 2025 Quarter End:

1.15x

Q3 2025 Average1:

1.10x

Revolving Credit Facility1

Unfunded Commitment Activity

Revolver Capacity

$1,675

Unfunded Commitments (See Note 8 in 6/30/25 10-Q)

$341

Drawn on Revolver

($609)

Extinguished Unfunded Commitments

($20)

Unrestricted Cash Balance

$63

New Unfunded Commitments

$44

Issued Letters of Credit

($20)

Net Drawdown of Unfunded Commitments

($28)

Total Liquidity (Pre-Unfunded Commitments)

$1,109

Total Unfunded Commitments

$337

Available Unfunded Commitments2

($174)

Unavailable Unfunded Commitments2

($163)

Total Liquidity (Burdened for Unfunded Commitments)

$935

Available Unfunded Commitments2

$174

Three Months Ended

(unaudited)

September 30, 2025

December 31, 2024

September 30, 2024

Investments at Fair Value

$

3,376.3

$

3,518.4

$

3,441.1

Total Assets

$

3,509.3

$

3,582.2

$

3,529.9

Net Asset Value Per Share

$

17.14

$

17.16

$

17.12

Supplemental Dividend Per Share

$

0.03

$

0.07

$

0.05

Adjusted Net Asset Value Per Share (1)

$

17.11

$

17.09

$

17.07

Investment Income

$

109.4

$

123.7

$

119.2

Net Investment Income

$

50.7

$

57.6

$

54.9

Net Income

$

44.6

$

51.0

$

40.7

Accrued Capital Gains Incentive Fee Expense

$

(1.1

)

$

(1.0

)

$

(2.2

)

Adjusted Net Investment Income (2)

$

49.6

$

56.6

$

52.7

Adjusted Net Income (2)

$

43.5

$

50.0

$

38.4

Net Investment Income Per Share

$

0.54

$

0.62

$

0.59

Net Income Per Share

$

0.47

$

0.55

$

0.44

Accrued Capital Gains Incentive Fee Expense Per Share

$

(0.01

)

$

(0.01

)

$

(0.02

)

Adjusted Net Investment Income Per Share (2)

$

0.53

$

0.61

$

0.57

Adjusted Net Income Per Share (2)

$

0.46

$

0.54

$

0.41

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

12.5

%

14.4

%

13.7

%

Annualized Return on Equity (Net Income) (3)

11.0

%

12.8

%

10.2

%

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

12.3

%

14.2

%

13.2

%

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

10.8

%

12.5

%

9.6

%

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

11.4

%

12.3

%

13.1

%

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

11.7

%

12.5

%

13.4

%

Percentage of Debt Investment Commitments at Floating Rates

96.3

%

97.2

%

98.8

%

September 30,

December 31,

2025

2024

Assets

Investments at fair value

Non-controlled, non-affiliated investments (amortized cost of $3,246,833 and $3,450,644, respectively)

$

3,309,972

$

3,453,317

Controlled, affiliated investments (amortized cost of $97,139 and $88,509, respectively)

66,339

65,095

Total investments at fair value (amortized cost of $3,343,972 and $3,539,153, respectively)

3,376,311

3,518,412

Cash and cash equivalents (restricted cash of $20,137 and $22,362, respectively)

83,159

27,328

Interest receivable

31,193

30,518

Prepaid expenses and other assets

18,598

5,967

Total Assets

$

3,509,261

$

3,582,225

Liabilities

Debt (net of deferred financing costs of $26,167 and $23,837, respectively)

$

1,834,285

$

1,901,142

Management fees payable to affiliate

12,797

12,953

Incentive fees on net investment income payable to affiliate

10,527

12,013

Incentive fees on net capital gains accrued to affiliate

1,768

5,071

Other payables to affiliate

2,987

3,635

Other liabilities

27,190

39,882

Total Liabilities

1,889,554

1,974,696

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, 95,158,175
   and 94,325,686 shares issued, respectively; and 94,493,925 and 93,661,436
   shares outstanding, respectively

952

943

Additional paid-in capital

1,537,514

1,519,337

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

(10,459

)

(10,459

)

Distributable earnings

91,700

97,708

Total Net Assets

1,619,707

1,607,529

Total Liabilities and Net Assets

$

3,509,261

$

3,582,225

Net Asset Value Per Share

$

17.14

$

17.16

Three Months Ended

Nine Months Ended

September 30, 2025

September 30, 2024

September 30, 2025

September 30, 2024

Income

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

Interest from investments

$

92,221

$

103,363

$

295,098

$

308,478

Paid-in-kind interest income

6,883

6,218

18,026

23,761

Dividend income

268

3,251

1,563

5,847

Other income

7,397

3,951

18,465

13,737

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

106,769

116,783

333,152

351,823

Investment income from controlled, affiliated investments:

Interest from investments

2,672

2,438

7,649

6,989

Other income

3

2

7

10

Total investment income from controlled, affiliated investments

2,675

2,440

7,656

6,999

Total Investment Income

109,444

119,223

340,808

358,822

Expenses

Interest

31,385

38,492

98,003

116,759

Management fees

13,081

13,029

39,082

38,390

Incentive fees on net investment income

10,527

11,175

33,132

33,517

Incentive fees on net capital gains

(1,054

)

(2,245

)

(3,303

)

(4,424

)

Professional fees

2,022

1,911

6,544

5,776

Directors’ fees

206

215

702

643

Other general and administrative

1,507

1,352

4,124

3,979

Total expenses

57,674

63,929

178,284

194,640

Management and incentive fees waived (Note 3)

(284

)

(330

)

(990

)

(1,024

)

Net Expenses

57,390

63,599

177,294

193,616

Net Investment Income Before Income Taxes

52,054

55,624

163,514

165,206

Income taxes, including excise taxes

1,374

698

4,016

2,774

Net Investment Income

50,680

54,926

159,498

162,432

Unrealized and Realized Gains (Losses)

Net change in unrealized gains (losses):

Non-controlled, non-affiliated investments

(3,887

)

(2,502

)

60,466

(19,669

)

Controlled, affiliated investments

(3,019

)

(19

)

(7,385

)

(2,399

)

Translation of other assets and liabilities in foreign currencies

756

(10,305

)

(36,052

)

(7,220

)

Income tax provision

605

(1,456

)

605

(1,456

)

Total net change in unrealized gains (losses)

(5,545

)

(14,282

)

17,634

(30,744

)

Realized gains (losses):

Non-controlled, non-affiliated investments

768

83

(34,919

)

3,947

Foreign currency transactions

(366

)

(72

)

(719

)

(60

)

Income tax provision

(937

)

—

(937

)

—

Total net realized gains (losses)

(535

)

11

(36,575

)

3,887

Total Net Unrealized and Realized Gains (Losses)

(6,080

)

(14,271

)

(18,941

)

(26,857

)

Increase (Decrease) in Net Assets Resulting from Operations

$

44,600

$

40,655

$

140,557

$

135,575

Earnings per common share—basic and diluted

$

0.47

$

0.44

$

1.50

$

1.48

Weighted average shares of common stock outstanding—basic and diluted

94,245,993

93,024,154

93,964,387

91,602,160

Three Months Ended

($ in millions)

September 30, 2025

September 30, 2024

New investment commitments:

Gross originations (1)

$

3,735.0

$

2,502.0

Less: Syndications/sell downs (1)

3,347.3

2,232.7

Total new investment commitments

$

387.7

$

269.3

Principal amount of investments funded:

First-lien

$

253.1

$

189.0

Second-lien

—

—

Mezzanine

—

—

Equity and other

—

—

Structured Credit

98.7

—

Total

$

351.8

$

189.0

Principal amount of investments sold or repaid:

First-lien

$

302.0

$

84.2

Second-lien

—

—

Mezzanine

—

4.9

Equity and other

0.8

—

Structured Credit

—

1.1

Total

$

302.8

$

90.2

Number of new investment commitments in
   new portfolio companies (2)

41

8

Average new investment commitment amount in
   new portfolio companies (2)

$

7.3

$

30.2

Weighted average term for new investment
   commitments in new portfolio companies
   (in years) (2)

7.8

6.3

Percentage of new debt investment commitments
   at floating rates

100.0

%

75.9

%

Percentage of new debt investment commitments
   at fixed rates

0.0

%

24.1

%

Weighted average interest rate of new
   investment commitments

10.3

%

12.0

%

Weighted average spread over reference rate of new
   floating rate investment commitments

6.6

%

6.8

%

Weighted average interest rate on investments
   fully sold or paid down

12.6

%

13.0

%