Blackstone Secured Lending Fund

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2025

OR

For the transition period from to

Commission File Number 814-01299

(Exact name of Registrant as specified in its Charter)

Registrant’s telephone number, including area code:(212) 503-2100

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

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☒ No ☐

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐No ☒

Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act:

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. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Act). YES ☐ NO☒

As of June 30, 2025, the aggregate market value of the common shares of beneficial interest, par value $0.001 per share (“Common Shares”) held by non-affiliates of the Registrant was $6,968 million.

The number of Common Shares outstanding as of February 18, 2026 was 232,279,811.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This report contains forward-looking statements that involve substantial risks and uncertainties. Such statements involve known and unknown risks, uncertainties and other factors and undue reliance should not be placed thereon. These forward-looking statements are not historical facts, but rather are based on current expectations, estimates and projections about Blackstone Secured Lending Fund (together, with its consolidated subsidiaries, the “Company,” “we,” “us” or“our”), our current and prospective portfolio investments, our industry, our beliefs and opinions, and our assumptions. Words such as “anticipates,” “expects,” “intends,” “plans,” “will,” “may,” “continue,” “believes,” “seeks,” “estimates,” “would,” “could,” “should,” “targets,” “projects,” “outlook,” “potential,” “predicts” and variations of these words and similar expressions are intended to identify forward-looking statements. These statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, some of which are beyond our control and difficult to predict and could cause actual results to differ materially from those expressed or forecasted in the forward-looking statements, including without limitation:

•our future operating results;

•our business prospects and the prospects of the companies in which we may invest;

•the impact of the investments that we expect to make;

•our ability to raise sufficient capital and buy back shares to execute our investment strategy;

•general economic, logistical and political trends and other external factors, including inflation, trade policies, and recent supply chain disruptions and their impacts on our portfolio companies and on the industries in which we invest;

•the ability of our portfolio companies to achieve their objectives;

•our current and expected financing arrangements and investments;

•changes in the general interest rate environment;

•the adequacy of our cash resources, financing sources and working capital;

•the timing and amount of cash flows, distributions and dividends, if any, from our portfolio companies;

•our contractual arrangements and relationships with third parties;

•actual and potential conflicts of interest with Blackstone Private Credit Strategies LLC (the “Adviser”), Blackstone Credit BDC Advisors LLC (the“Sub-Adviser” and together with the Adviser, the“Advisers”) or any of their affiliates;

•the dependence of our future success on the general economy and its effect on the industries in which we may invest;

•our use of financial leverage including the use of borrowed money to finance a portion of our investments and the availability of equity and debt capital on favorable terms or at all;

•our business prospects and the prospects of our portfolio companies, including our and their ability to effectively respond to macroeconomic effects;

•the ability of the Advisers to source suitable investments for us and to monitor and administer our investments;

•the impact of future acquisitions and divestitures;

•the ability of the Advisers or their affiliates to attract and retain highly talented professionals;

•general price and volume fluctuations in the stock market;

•our ability to maintain our qualification as a regulated investment company (“RIC”) and as a business development company (“BDC”);

•the impact on our business of U.S. and international financial reform legislation, rules and regulations;

•the effect of changes to tax legislation and our tax position; and

•the tax status of the enterprises in which we may invest.

Although we believe that the assumptions on which these forward-looking statements are based are reasonable, any of those assumptions could prove to be inaccurate, and as a result, the forward-looking statements based on those assumptions also could be inaccurate. In light of these and other uncertainties, the inclusion of any projection or forward-looking statement in this report should not be regarded as a representation by us that our plans and objectives will be achieved. These risks and uncertainties include those described or identified in the section entitled “Item 1A. Risk Factors” and elsewhere in this report. These projections and forward-looking statements apply only as of the date of this report. Moreover, we assume no duty and do not undertake to update the forward-looking statements, whether as a result of new information, future developments or otherwise, except as required by applicable law. You are advised to consult any additional disclosures that we make directly to you or through reports that we have filed or in the future file with the Securities and Exchange Commission including annual reports on Form 10-K, registration statements on Form N-2, quarterly reports on Form 10-Q and current reports on Form 8-K. This annual report on Form 10-K contains statistics and other data that have been obtained from or compiled from information made available by third-party service providers. We have not independently verified such statistics or data.

Because we are an investment company, the forward-looking statements and projections contained in this report are excluded from the safe harbor protection provided by Section 21E of the U.S. Securities Exchange Act of 1934, as amended (the“Exchange Act”).

Risk Factor Summary

The following is only a summary of the principal risks that may materially adversely affect our business, financial condition, results of operations and cash flows. The following should be read in conjunction with the more complete discussion of the risk factors we face, which are set forth in the section entitled “Item 1A. Risk Factors” in this report.

Risks Related to Our Business and Structure

•Price declines in the medium and large-sized U.S. corporate debt market may adversely affect the fair value of our portfolio and our market price.

•Our ability to achieve our investment objectives depends on the ability of the Advisers to manage and support our investment process largely through relationships with private equity sponsors, investment banks and commercial banks.

•Our Board of Trustees (the“Board” or “Board of Trustees”) may change our operating policies and strategies or amend our Fourth Amended and Restated Declaration of Trust (the“Declaration of Trust”) without prior notice or shareholder approval, the effects of which may be adverse to our results of operations and financial condition.

•We may face increasing competition for investment opportunities, have difficulty sourcing investment opportunities and experience fluctuations in our quarterly results.

•As required by the Investment Company Act of 1940, as amended (together with the rules and regulations promulgated thereunder, the“1940 Act”), a significant portion of our investment portfolio is and will be recorded at fair value as determined in good faith by our Board and, as a result, there is and will be uncertainty as to the value of our portfolio investments.

•There is a risk that investors in our Common Shares may not receive distributions or that our distributions may decrease over time.

•Changes in laws or regulations governing our operations and the possibility of increased regulatory focus on areas related to our business could result in additional burdens on our business.

•General economic conditions could adversely affect the performance of our investments and our market price, including recessionary fears, geopolitical events and inflation.

•We and our portfolio companies and service providers may be subject to cybersecurity risks and our business could be adversely affected by changes to data protection laws and regulations.

Risks Related to Our Investments

•We generally will not control our portfolio companies and our investments in prospective portfolio companies may be risky.

•Economic recessions or downturns or restrictions on trade could impair our portfolio companies and adversely affect our operating results.

•Our portfolio companies may incur debt that ranks equally with, or senior to, our investments in such companies and breach covenants or defaults on such debt.

•We are exposed to risks associated with changes in interest rates.

•Second priority liens on collateral securing debt investments that we make to our portfolio companies may be subject to control by senior creditors with first priority liens.

•Our portfolio may be concentrated in a limited number of industries, which may subject us to specific risks.

Risks Related to the Advisers and Their Affiliates

•The Advisers and their affiliates, including our officers and some of our trustees, face conflicts of interest caused by compensation arrangements with us and our affiliates, which could result in actions that are not in the best interests of our shareholders.

•We may be obligated to pay the Adviser, and the Adviser may be obligated to pay the Sub-Adviser, incentive compensation even if we incur a net loss due to a decline in the value of our portfolio and the compensation paid to the Adviser and the Sub-Adviser is determined without independent assessment.

•The Advisers rely on key personnel, the loss of any of whom could impair its ability to successfully manage us.

Risks Related to Business Development Companies

•The requirement that we invest a sufficient portion of our assets in assets of the type listed in Section 55(a) of the 1940 Act (“Qualifying Assets”) could preclude us from investing in accordance with our current business strategy; conversely, the failure to invest a sufficient portion of our assets in Qualifying Assets could result in our failure to maintain our status as a BDC.

•Regulations governing our operation as a BDC and RIC will affect our ability to raise, and the way in which we raise, additional capital or borrow for investment purposes.

Risks Related to Debt Financing

•We borrow money, which magnifies the potential for loss on amounts invested in us and may increase the risk of investing in us.

•Provisions in a credit facility may limit our investment discretion.

•We are subject to risks associated with the unsecured notes and debt securitizations that we have issued and our credit facilities.

Federal Income Tax Risks

•We will be subject to corporate-level income tax if we are unable to maintain RIC tax treatment under Subchapter M of the Internal Revenue Code of 1986, as amended (together with the rules and regulations promulgated thereunder, the“Code”) or to satisfy RIC distribution requirements.

•Our portfolio investments may present special tax issues.

•Legislative or regulatory tax changes could adversely affect investors.

Risks Related to an Investment in the Common Shares

•Shares of closed-end management investment companies, including BDCs, often trade at a discount to their net asset value.

•An investment in our Common Shares involves a high degree of risk and the market price of our securities could fluctuate significantly.

•There is a risk that investors in our equity securities will not receive distributions or that our distributions do not grow over time and a portion of our distributions could be a return of capital.

Website Disclosure

We use our website (www.bxsl.com) as a channel of distribution of company information. The information we post through this channel may be deemed material. Accordingly, investors should monitor this channel, in addition to following our press releases, SEC filings and public conference calls, and webcasts. In addition, you may automatically receive email alerts and other information about the Company when you enroll your email address by visiting the “Contact Us” section of our website at http://ir.bxsl.com. The contents of our website and any alerts are not, however, a part of this report.

Other Disclosure

To the extent required by laws implementing the European Union Directive on Alternative Investment Fund Managers (the “Directive”) in any relevant European Economic Area member state, the information in respect of the Company required to be disclosed pursuant to Article 23(4) and (5) of the Directive will be made available to each applicable shareholder. In respect of the period ended December 31, 2025, there have been no material changes to the information listed in Article 23 of the Directive.