OMEROS CORP

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: 001-34475

(Exact name of registrant as specified in its charter)

(206) 676-5000

(Registrant’s telephone number, including area code)

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, as amended, 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 Exchange Act). Yes☐ No ☒

The aggregate market value of the voting and non-voting common stock held by non-affiliates of the registrant as of the last business day of the registrant’s most recently completed second fiscal quarter was $172,381,173.

As of March 27, 2026, the number of outstanding shares of the registrant’s common stock, par value $0.01 per share, was 71,996,171.

DOCUMENTS INCORPORATED BY REFERENCE

Specified portions of the registrant’s proxy statement with respect to the 2026 Annual Meeting of Shareholders, which is to be filed pursuant to Regulation 14A within 120 days after the end of the registrant’s fiscal year ended December 31, 2025, are incorporated by reference into Part III of this Form 10-K.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934 (the “Exchange Act”), which are subject to the “safe harbor” created by those sections for such statements. Forward-looking statements are based on our management’s beliefs and assumptions and on currently available information. All statements other than statements of historical fact are “forward-looking statements.” Terms such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “goal,” “intend,” “likely,” “may,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “target,” “will,” “would,” and similar expressions and variations thereof are intended to identify forward-looking statements, but these terms are not the exclusive means of identifying such statements. Examples of these statements include, but are not limited to, statements regarding:

● our future performance, financial position and results of operations, including our expectations relating to income from product sales revenue, milestone payments potentially payable to us under certain agreements and other sources, our estimates of future operating expenses and projections regarding how long our existing cash, cash equivalents and short-term investments will fund our anticipated operating expenses, capital expenditures, and debt service obligations;

● the availability of capital resources, including our ability to raise additional capital through the capital markets or one or more future equity offerings, debt financings, industry collaborations, licensing arrangements, asset sales, or other means;

● our plans for sales, marketing, and distribution of YARTEMLEA® and our estimates and expectations regarding coverage and reimbursement for YARTEMLEA;

● our expectations regarding anticipated or potential paths to regulatory approval of YARTEMLEA by the European Medicines Agency (“EMA”), including whether a decision on our marketing authorization application (“MAA”) for narsoplimab in hematopoietic stem cell transplant-associated thrombotic microangiopathy (“TA-TMA”) will be issued within the expected timeframe, and whether the EMA or any other regulatory authority will ultimately grant approval for narsoplimab in TA-TMA or in any other indication;

● our expectations regarding supply and manufacturing of YARTEMLEA drug substance and finished drug product and the performance of the contract manufacturers on whom we rely to manufacture YARTEMLEA for commercial sale and for support with associated regulatory obligations, and our expectations related to manufacturing and supply of our product candidates in development;

● our expectations about the commercial competition that YARTEMLEA or our product candidates, if commercialized, face or may face;

● our expectations relating to the Asset Purchase and License Agreement (the “APLA”), by and between Omeros Corporation and Novo Nordisk Health Care AG (“Novo Nordisk”), including Novo Nordisk’s anticipated development plans for zaltenibart, anticipated outcomes of such plans and the amounts potentially payable to us under the terms of the APLA;

● our expectations regarding amounts potentially payable to us based on sales of our former commercial ophthalmology product OMIDRIA® under relevant agreements;

● our expectations regarding the clinical, therapeutic, and competitive benefits and importance of YARTEMLEA, zaltenibart, and the product candidates within our development pipeline;

● our expectations regarding planned or ongoing clinical trials, including anticipated strategies for future clinical development of our internal or partnered products and development candidates, and our ability or our partners’ ability to design, initiate and/or successfully complete clinical trials and other studies;

● our involvement in existing or potential claims, legal proceedings, and administrative actions, and the merits, potential outcomes and effects of both existing and potential claims, legal proceedings, and administrative actions, as well as regulatory determinations, on our business, prospects, financial condition, and results of operations;

● the extent of protection that our patents provide and that our pending patent applications will provide, if patents are issued from such applications, for our technologies, programs, products and product candidates;

● our ability to consummate licensing, partnering or other transactions and the benefits, if any, we would receive from any such transactions; and

● the factors on which we base our estimates for accounting purposes and our expectations regarding the effect of changes in accounting guidance or standards on our operating results.

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Our actual results could differ materially from those anticipated in these forward-looking statements for many reasons, including the risks, uncertainties and other factors described in Item 1A of Part I of this Annual Report on Form 10-K under the heading “Risk Factors” and in Item 7 of Part II under the heading “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and in our other filings with the Securities and Exchange Commission (“SEC”). Given these risks, uncertainties and other factors, actual results or anticipated developments may not be realized or, even if substantially realized, they may not have the expected consequences to or effects on our company, business or operations. Accordingly, you should not place undue reliance on these forward-looking statements, which represent our estimates and assumptions only as of the date of the filing of this Annual Report on Form 10-K. You should read this Annual Report on Form 10-K completely and with the understanding that our actual results in subsequent periods may materially differ from current expectations. Except as required by applicable law, including the securities laws of the United States and the rules and regulations of the SEC, we assume no obligation to update or revise any forward-looking statements contained herein, whether as a result of any new information, future events or otherwise.

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