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

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%

Total Investment Income

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

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

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

$1

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

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

%

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

%

96.3

%

97.0

%

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

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

9

1

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

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

3

6

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

%