☒QUARTERLY REPORT PURSUANT TO SECTION13 OR 15(d)OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period endedSeptember 30, 2025 OR ☐TRANSITION REPORT PURSUANT TO SECTION13 OR 15(d)OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number:814-00659 PROSPECT CAPITAL CORPORATION (Exact name of registrant as specified in its charter) Securities registered pursuant to Section 12(b) of the Act: Indicate by check mark whether the registrant (1)has filed all reports required to be filed by Section13 or 15(d) of the Securities Exchange Actof 1934 during the preceding 12months (or for such shorter period that the registrant was required to file such reports), and (2)has been subjectto such filing requirements for the past 90days.YesýNoo Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant toRule405 of RegulationS-T (§232.405 of this chapter) during the preceding 12months (or for such shorter period that the registrant wasrequired to submit such files).YesýNoo Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reportingcompany, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”“smaller reporting company,” and“emerging growth company” in Rule12b-2 of the Exchange Act. Large accelerated filerýAccelerated fileroNon-accelerated fileroSmallerreportingcompanyoEmerging growth companyo(Do not check if a smaller reporting company) If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complyingwith any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.o Indicate by check mark whether the registrant is a shell company (as defined in Rule12b-2 of the Act).Yeso Noý As of November5, 2025, there were470,910,990shares of the registrant’s common stock, $0.001 par value per share, outstanding. Table of Contents PageForward-Looking Statements3PART IFINANCIAL INFORMATIONItem 1.Financial StatementsConsolidated Statements of Assets and Liabilities as of September 30, 2025 (unaudited) and June 30, 20254Consolidated Statements of Operations for the three months ended September 30, 2025 and September 30, 2024(unaudited)5Consolidated Statements of Changes in Net Assets and Temporary Equity for the three months ended September 30, 2025and September 30, 2024 (unaudited)7Consolidated Statements of Cash Flows for the three months ended September 30, 2025 and September 30, 2024(unaudited)8Consolidated Schedules of Investments as of September 30, 2025 (unaudited) and June 30, 20259Notes to Consolidated Financial Statements (unaudited)55Item 2.Management’s Discussion and Analysis of Financial Condition and Results of Operations122Item 3.Quantitative and Qualitative Disclosures About Market Risk152Item 4.Controls and Procedures154PART IIOTHER INFORMATIONItem 1.Legal Proceedings155Item 1A.Risk Factors155Item 2.Unregistered Sales of Equity Securities and Use of Proceeds158Item 3.Defaults Upon Senior Securities158Item 4.Mine Safety Disclosures158Item 5.Other Information159Item 6.Exhibits163Signatures FORWARD-LOOKING STATEMENTS This report contains information that may constitute “forward-looking statements.” Generally, the words “believe,” “expect,” “intend,”“estimate,” “anticipate,” “project,” “will,” “should,” “could,” “may,” “plan” and similar expressions identify forward-looking statements, whichgenerally are not historical in nature. However, the absence of these words or similar expressions does not mean that a statement is not forward-looking. All statements that address operating performance, events or developments that we expect or anticipate will occur in the future—including statements relating to volume growth, share of sales and earnings per share growth, and statements expressing general views aboutfuture operating results—are forward-looking statements. Management believes that these forward-looking statements are reasonable as andwhen made. However, caution should be taken not to place undue reliance on any such forward-looking statements because such statementsspeak only as of the date when made. We undertake no obligation to publicly update or revise any forward-looking statements, whether as aresult of new information, future events or otherwise, except as required by law. In addition, forward-looking statements are subject to certainrisks and uncertainties that could cause actual results to differ materially from our historical experience and our present expectations orprojections. These risks and uncertainties include, but are not limited to, those described in Part II, “Item 1A. Risk Factors” and elsewhere inthis report and in our Annual Report on Form 10-K for the year ended June 30, 2025, and those described from time to time in reports that wehave filed or in the