PROSPECT CAPITAL CORPORATION

(Exact name of Registrant as specified in its charter)

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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  ý     No  o

Indicate by check mark whether the Registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted 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 and post such files). Yes  o     No  o

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

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes  o     No  ý

Indicate the number of shares outstanding of each of the issuer's classes of common stock as of the latest practicable date.

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Table of Contents

FORWARD-LOOKING STATEMENTS

This report contains information that may constitute “forward-looking statements.” Generally, the words “believe,” “expect,”

“intend,” “estimate,” “anticipate,” “project,” “will” and similar expressions identify forward-looking statements, which generally 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 about future operating results—are forward-looking statements. Management believes that these forward-looking statements are reasonable as and when made. However, caution should be taken not to place undue reliance on any such forward-looking statements because such statements speak only as of the date when made. We undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law. In addition, forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from our historical experience and our present expectations or projections. These risks and uncertainties include, but are not limited to, those described in Part II, “Item 1A. Risk Factors” and elsewhere in this report and in our Annual Report on Form 10-K for the year ended June 30, 2017 , and those described from time to time in our future reports filed with the Securities and Exchange Commission.