ARDELYX, INC.

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: 001-36485

(Exact Name of Registrant as Specified in Its Charter)

(510) 745-1700

(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 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 Exchange Act). Yes ☐No ☒

The aggregate market value of the Registrant’s 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, June 30, 2025, based on the last reported sales price of the Registrant’s common stock on the Nasdaq Global Market of $3.92 per share was $923,706,456.

The number of shares of Registrant’s Common Stock outstanding as of February 12, 2026, was 245,247,427.

DOCUMENTS INCORPORATED BY REFERENCE:

Portions of the Registrant’s Definitive Proxy Statement for its 2026 Annual Meeting of Stockholders, which will be filed with the Commission within 120 days of December 31, 2025, the close of the Registrant’s 2025 fiscal year, are incorporated by reference into Part III of this Report.

NOTE REGARDING FORWARD-LOOKING STATEMENTS

Unless the context requires otherwise, in this Annual Report on Form 10-K, the terms “Ardelyx,” “Company,” “we,” “us” and “our” refer to Ardelyx, Inc.

This Annual Report on Form 10-K contains forward-looking statements that involve risks and uncertainties. Any statements contained herein that are not statements of historical facts may be deemed to be forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,” “continue,” “could,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “predict,” “potential,” “positioned,” “seek,” “should,” “target,” “will,” “would,” and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:

•estimates of our expenses, future revenue, capital requirements, our needs for additional financing and our ability to obtain additional capital; and

•other risks and uncertainties, including those under the caption “Risk Factors.”

We have based these forward-looking statements largely on management’s current expectations, estimates, forecasts and projections about our business and the industry in which we operate and management’s beliefs and assumptions, and these forward-looking statements are not guarantees of future performance or development and involve known and unknown risks, uncertainties and other factors that are in some cases beyond our control, that could cause actual outcomes or results to differ materially from those expressed or implied by such forward-looking statements. Factors that could cause actual results or conditions to differ from those anticipated by these and other forward-looking statements include those more fully described in the “Item 1A. Risk Factors” section and elsewhere in this Annual Report on Form 10-K. Except as required by law, we assume no obligation to update any forward-looking statement publicly, or to revise any forward-looking statement to reflect events or developments occurring after the date of this Annual Report on Form 10-K, even if new information becomes available in the future. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in any such forward-looking statement.

SUMMARY OF PRINCIPAL RISKS ASSOCIATED WITH OUR BUSINESS

The principal risks and uncertainties affecting our business include the following:

•We have incurred losses in each year since our inception, and if we are unable to continue to increase revenue and/or, depending upon our pursuit of future business opportunities, we may not achieve expected cash flow positivity, and even if we do, we may not be able to sustain cash flow positivity quarter over quarter and year over year.

•We may require additional financing for the foreseeable future as we invest in the growth of IBSRELA and XPHOZAH in the U.S. and build a pipeline. The inability to access necessary capital when needed on acceptable terms, or at all, could force us to delay or limit our pursuit of other future business opportunities.

•We are substantially dependent on the successful commercialization of IBSRELA, and there is no guarantee that we will maintain sufficient market acceptance for IBSRELA, grow market share for IBSRELA, secure and maintain adequate coverage and reimbursement for IBSRELA, or generate sufficient revenue from product sales of IBSRELA.

•There is no guarantee that we will achieve sufficient market acceptance for XPHOZAH, or that we will be able to secure and maintain adequate coverage and reimbursement for XPHOZAH, or generate sufficient revenue from product sales of XPHOZAH. The inclusion of XPHOZAH in the ESRD PPS creates additional uncertainty as to the commercial opportunity for XPHOZAH.

•XPHOZAH became part of the ESRD PPS on January 1, 2025, which means coverage for XPHOZAH for Medicare beneficiaries is no longer available under Medicare Part D; this resulted in a negative and material impact on our XPHOZAH revenue in 2025; and the continued lack of Medicare Part D coverage for XPHOZAH will result in a materially lower pace of revenue growth as compared to expectations before XPHOZAH became part of the ESRD PPS.

•Current and future healthcare reform legislation, regulation or action by the current administration may increase the difficulty and cost for us to commercialize our approved products and may adversely affect the prices we, or they, may obtain and may have a negative impact on our business and results of operations.

•IBSRELA and/or XPHOZAH may cause undesirable side effects or have other properties that could limit the commercial success of the products.

•Third-party payor coverage and reimbursement status of newly commercialized products are uncertain. Failure to obtain or maintain adequate coverage and reimbursement for IBSRELA and XPHOZAH could limit our ability to market those products and decrease our ability to generate revenue.

•We rely completely on third parties, including certain single-source suppliers, to manufacture IBSRELA and XPHOZAH. If they are unable to comply with applicable regulatory requirements, unable to source sufficient raw materials, experience manufacturing or distribution difficulties or are otherwise unable to manufacture sufficient quantities to meet demand, our commercialization of IBSRELA and XPHOZAH may be materially harmed.

•Our operating activities may be restricted as a result of covenants related to the indebtedness under our loan and security agreement with SLR, as amended, and we may be required to repay the outstanding indebtedness in an event of default, which could have a materially adverse effect on our business.

The summary risk factors described above should be read together with the text of the full risk factors below in the section titled “Risk Factors” and the other information set forth in this Annual Report on Form 10-K, including our financial statements and the related notes, as well as in other documents that we file with the U.S. SEC. The risks summarized above or described in full below are not the only risks that we face. Additional risks and uncertainties not precisely known to us or that we currently deem to be immaterial may also materially adversely affect our business, financial condition, results of operations, and future growth prospects.

NOTE REGARDING TRADEMARKS

ARDELYX®, IBSRELA® and XPHOZAH®are trademarks of Ardelyx. All other trademarks, trade names and service marks appearing in this Annual Report on Form 10-K are the property of their respective owners.