ARDELYX, INC.

NOTE 1. NATURE OF OPERATIONS

We are a commercial-stage biopharmaceutical company focused on the development and commercialization of innovative medicines that meet significant unmet medical needs. We currently market two therapies from the active ingredient tenapanor, a sodium/hydrogen exchanger (NHE3) inhibitor that was discovered and developed by Ardelyx. NHE3 is an antiporter expressed on the apical surface of the small and large intestines. Tenapanor is a minimally absorbed, small molecule therapy.

Tenapanor, branded as IBSRELA®, is approved in the U.S. for the treatment of adults with irritable bowel syndrome with constipation (IBS-C). We are seeking to further expand the IBSRELA eligible patient population to include patients with chronic idiopathic constipation (CIC), and have initiated a Phase 3 clinical trial evaluating tenapanor in adult CIC patients.

Tenapanor, branded as XPHOZAH®, is approved in the U.S. to reduce serum phosphorus in adults with chronic kidney disease on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy.

We are also developing a next-generation NHE3 inhibitor, RDX10531, which has demonstrated in preclinical models to have improved solubility and potency compared to tenapanor. We believe that RDX10531 can have application across multiple therapeutic areas.

We operate inone business segment, which is the development and commercialization of biopharmaceutical products. Refer to Note 12. Segment Reporting for further segment reporting information.

Basis of Presentation

These condensed financial statements have been prepared in accordance with U.S. GAAP and pursuant to the requirements of the SEC for interim reporting. As permitted under those rules and regulations, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted. These condensed financial statements have been prepared on the same basis as our most recent annual financial statements and, in the opinion of management, reflect all normal and recurring adjustments necessary to present fairly our financial position, results of operations, changes in stockholders’ equity and cash flows for the interim periods presented.

Certain prior year amounts have been reclassified to conform to the current year presentation on the condensed statements of operations and comprehensive loss to include the “cost of product sales” and the “other cost of revenue” captions within the “cost of sales” caption. Certain prior year amounts have also been reclassified to conform to the current year presentation in Note 12. Segment Reporting. These reclassifications had no effect on the previously reported results of operations.

The accompanying condensed financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto included in our 2025 Form 10-K. The results for the three months ended March 31, 2026 are not necessarily indicative of results to be expected for the entire year ending December 31, 2026, or for any other interim period or future year.

Refer to the Summary of Abbreviated Terms at the end of this Quarterly Report on Form 10-Q for definitions of terms used throughout the document.

Critical Accounting Policies and Estimates

The preparation of financial statements requires management to make estimates, judgments and assumptions. The most significant assumptions are estimates used in our revenue gross-to-net accruals and other assumptions. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could materially differ from those estimates. Our critical accounting policies and estimates are discussed in our 2025 Form 10-K.

Concentration of Credit Risk

Financial instruments that potentially subject us to significant concentrations of credit risk consist primarily of cash, cash equivalents, short-term investments and accounts receivable. We are exposed to credit risks in the event of default by the counterparties to the extent of the amount recorded in our balance sheets. Cash, cash equivalents and short-term investments are invested through banks and other financial institutions in the U.S.

Recent Accounting Pronouncements

Recent Accounting Pronouncement Not Yet Adopted

In November 2024, the FASB issued ASU No. 2024-03, Income Statement (Topic 220) -Reporting Comprehensive Income - Expense Disaggregation Disclosures, Disaggregation of Income Statement Expenses, which requires public companies to disclose, in interim and annual reporting periods, additional information about certain expenses in the financial statements. The new disclosure requirements are effective for the Company’s annual periods beginning January 1, 2027, and interim periods beginning January 1, 2028, with early adoption permitted, and may be applied either prospectively or retrospectively. The Company is in the process of evaluating the impact of this new guidance on its disclosures.

NOTE 2. CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS

The following table summarizes our cash, cash equivalents and short-term investments:

Realized gains or losses have not been significant and are included in other income, net in our condensed statements of operations and comprehensive loss.

Unrealized losses as of March 31, 2026 and December 31, 2025 were not material. All of the short-term available-for-sale securities held as of March 31, 2026 and December 31, 2025 had contractual maturities of less than one year, andno investment was in a continuous unrealized loss position for more than one year. Therefore, we believe that it is more likely than not that the investments will be held until maturity or a forecasted recovery of fair value.

Based on our procedures under the expected credit loss model, including an assessment of unrealized losses in our portfolio, we concluded that any unrealized losses on our marketable securities were not attributable to credit and, therefore, we havenot recorded an allowance for credit losses for these securities as of March 31, 2026 and December 31, 2025.

See “Cash Equivalents” and “Short-Term Investments” captions of Note 2. Summary of Significant Accounting Policies of our 2025 Form 10-K for more information on our accounting policies for cash equivalents and short-term investments.

NOTE 3. FAIR VALUE MEASUREMENTS

Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows:

The following table sets forth the fair value of our financial assets that are measured or disclosed on a recurring basis by level within the fair value hierarchy:

Fair Value of Debt

The outstanding principal under our 2022 Loan Agreement is subject to a variable interest rate and therefore, we believe the carrying amount of the term loan facility approximated its fair value as of March 31, 2026 and December 31, 2025. See Note 8. Borrowing for a description of the Level 2 inputs used to estimate the fair value of the liability.

The carrying value of the deferred royalty obligation related to the sale of future royalties approximated its fair value as of March 31, 2026 and December 31, 2025, and is based on our current estimates of future royalties and commercialization milestones expected to be received by HCR over the life of the HCR Agreement. See Note 7. Deferred Royalty Obligation Related to the Sale of Future Royalties.

NOTE 4. INVENTORY

Inventory consisted of the following:

Prepaid commercial manufacturing with third-party CMOs not included in inventory was $18.9 million and $14.5 million as of March 31, 2026 and December 31, 2025, respectively. There were $4.2 million prepayments expected to be converted into inventory after 12 months as of March 31, 2026, compared tonone as of December 31, 2025.

NOTE 5. REVENUE

Disaggregation of total revenues by nature is as follows:

Product Sales, Net

Total product sales, net was as follows:

Concentrations

Gross product sales from Customers accounting for more than 10% of total revenues were as follows:

(1)The total of the above percentages exceeds 100% as the numerators used in the calculations represent gross product sales for each Customer, as opposed to product sales, net as presented in our condensed statements of operations and comprehensive loss.

GTN Adjustments

The activities and ending reserve balances for each significant category of GTN adjustments on product sales, net, which constitute variable consideration, were as follows:

(1)Adjustments to prior period provisions recorded in the current period were not material.

NOTE 6. COLLABORATION AND LICENSING AGREEMENTS

We have out-licensed to external partners for the development and commercialization of tenapanor outside of the U.S. We recognize revenue from our collaboration partnerships as licensing revenue, product supply revenue or non-cash royalty revenue related to the sale of future royalties. See Note 7. Collaboration and Licensing Agreements and “Collaboration and Licensing Revenue” caption of Note 2. Summary of Significant Accounting Policies of our 2025 Form 10-K for more information on the nature, purpose, significant rights and obligations of the parties, as well as our accounting policies for such revenue streams.

The following table summarizes total revenues by collaboration partner:

The following table presents changes in our current deferred revenue balances by collaboration partner:

The following table presents changes in our non-current deferred revenue balances by collaboration partner:

Significant developments and updates related to our collaboration partnerships in the three months ended March 31, 2026 and 2025 are discussed below.

Fosun Pharma

In March 2026, Fosun Pharma reported the first commercial sales of tenapanor, marketed under the Chinese trade name Wan Ti Le, for patients with CKD on hemodialysis with hyperphosphatemia in China. Pursuant to the terms of the license and manufacturing services agreements with Fosun Pharma, we are eligible to receive reimbursement of cost plus a reasonable overhead for the supply of product and tiered royalties on net sales ranging from the mid-teens to 20%.

In February 2025, we announced the NDA approval by China’s Center for Drug Evaluation of the NMPA for tenapanor in the control of serum phosphorus in adult patients with CKD on hemodialysis. This approval triggered a $5.0 million milestone to us, which was recorded as licensing revenue in our condensed statements of operations and comprehensive loss in the 2025 first quarter.

Knight - Former Collaboration Partner

Effective as of March 13, 2026, we entered into a termination agreement with Knight, pursuant to which we and Knight agreed to mutually terminate our exclusive license agreement for the development, commercialization and distribution of tenapanor in Canada for hyperphosphatemia and IBS-C. The decision was not related to any concerns regarding the safety, efficacy or quality of the product. Sales of IBSRELA in Canada were discontinued effective March 31, 2026. The termination did not have a material effect on our operations or financial results, and we do not expect it to adversely impact our operations or financial results in the future.

AstraZeneca

In connection with the AstraZeneca Termination Agreement, we recognized royalty expense as cost of sales in our condensed statements of operations and comprehensive loss of $8.8 million in the three months ended March 31, 2025. As of the end of the 2025 second quarter, we had fully recognized the maximum $75.0 million royalty obligation, which had been fully remitted as of the end of the 2025 third quarter.

NOTE 7. DEFERRED ROYALTY OBLIGATION RELATED TO THE SALE OF FUTURE ROYALTIES

We and HCR have an agreement in which HCR paid $15.0 million in exchange for royalty and commercialization milestone payments that we may receive under our Kyowa Kirin Agreement. See Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties of our 2025 Form 10-K for further discussion on the nature, purpose, significant rights and obligations of the parties, as well as our accounting policies regarding the HCR Agreement.

Payments received from HCR are recorded as a deferred royalty obligation on our balance sheets, which is being amortized as non-cash interest expense over the estimated life of the HCR Agreement using the effective interest method. The deferred royalty obligation will be effectively repaid over the life of the HCR Agreement as we remit to HCR royalties and commercialization milestones paid to us by Kyowa Kirin. We periodically assess the estimated amounts and timing of future royalties and commercialization milestone payments from Kyowa Kirin and, to the extent that the amount or timing of such payments is materially different than our original estimates, we prospectively adjust the imputed interest rate and the related amortization of the deferred royalty obligation.

A summary of financial information related to the HCR Agreement is as follows:

NOTE 8. BORROWING

The following table presents our outstanding term loans under the 2022 Loan Agreement:

The total unaccreted final fee was $5.4 million and $5.9 million as of March 31, 2026 and December 31, 2025, respectively.

As of March 31, 2026, our total future payment obligation related to the outstanding balance of the term loans, excluding interest payments, was $209.9 million, which is due on July 1, 2028.

As of March 31, 2026, there have been no changes to the principal, maturity, interest rates, interest payment terms and debt covenants since December 31, 2025. See Note 9. Borrowing of our 2025 Form 10-K for additional information regarding our 2022 Loan Agreement.

Effective as of April 28, 2026, we entered into the Sixth Amendment with SLR as collateral agent and the lenders party thereto. For additional information, refer to Note 15. Subsequent Events.

NOTE 9. LEASES

The following table provides additional details of our facility leases presented in our condensed balance sheets:

The following table presents the lease costs, which are included in our condensed statements of operations and comprehensive loss, and the supplemental cash flow information related to the leases:

The following table summarizes our undiscounted cash payment obligations for our operating lease liabilities as of March 31, 2026:

NOTE 10. STOCKHOLDERS’ EQUITY

In November 2025, we filed an automatic shelf registration statement on Form S-3ASR, which became effective upon filing, containing (i) a base prospectus, which covers the offering, issuance and sale from time to time in one or more offerings of our common stock, preferred stock, debt securities, warrants and/or units; and (ii) a prospectus supplement for the offering, issuance and sale of up to a maximum aggregate offering price of $100.0 million of our common stock that may be issued and sold from time to time under the 2025 Open Market Sales Agreement, deemed to be “at-the-market offerings.” Pursuant to the 2025 Open Market Sales Agreement, Jefferies, as sales agent, may receive a commission of up tothree percent of the gross sales price for shares of our common stock sold under the 2025 Open Market Sales Agreement. As of March 31, 2026, there have beenno sales of our common stock under the 2025 Open Market Sales Agreement.

NOTE 11. EQUITY INCENTIVE PLANS

Stock-Based Compensation Expense

Stock-based compensation expense for stock options, RSUs and our ESPP included in our condensed statements of operations and comprehensive loss was as follows:

A summary of our total unrecognized stock-based compensation expense, net of estimated forfeitures, as of March 31, 2026 is as follows:

Stock Options

A summary of our stock option activity and related information for the three months ended March 31, 2026 is as follows:

Restricted Stock Units

A summary of our RSU activity and related information for the three months ended March 31, 2026 is as follows:

Employee Stock Purchase Plan

During the three months ended March 31, 2026, we issued approximately 0.1 million shares of our common stock under the ESPP. The shares were purchased by employees at an average purchase price of $5.44 per share, resulting in proceeds to us of approximately $0.7 million.

NOTE 12. SEGMENT REPORTING

We operate in a single reportable segment. The Chief Executive Officer is our Chief Operating Decision Maker, who primarily uses aggregated net loss as reported on the condensed statements of operations and comprehensive loss to measure segment loss, supplemented by certain additional significant expense details reflected in the table below. There have been no changes in the determination of segmentation or the measurements used to determine reported segment loss discussed in our 2025 Form 10-K. See Note 17. Segment Reporting of our 2025 Form 10-K for more discussion on our segment reporting.

Detailed information regarding our single operating segment’s significant revenues, expenses and operating loss is as follows:

(1)Other revenues includes revenues from our collaboration partnerships, including licensing revenue, product supply revenue and non-cash royalty revenue related to the sale of future royalties.

(2)Cost of product sales includes the cost of commercial goods sold to our Customers, such as the cost of materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process and indirect overhead costs.

(3)Other cost of revenue includes the cost of materials sold to our collaboration partners under product supply agreements, certain costs related to capacity expansion at current and future CMOs and payments due to AstraZeneca. As of the end of the 2025 second quarter, the maximum $75.0 million royalty obligation under the AstraZeneca Termination Agreement had been fully recognized.

(4)Research and development, sellingand general and administrative expenses herein do not include stock-based compensation expenses.

(5)Other reconciliation items includes interest expense, non-cash interest expense related to the sale of future royalties, provision for income taxes and other income, net.

NOTE 13. NET LOSS PER SHARE

Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period and excludes any dilutive effect of stock-based awards. Diluted net loss per common share is computed giving effect to all potential dilutive common shares, including common stock issuable upon exercise of stock options, unvested restricted stock units and ESPP shares issuable pursuant to the current purchase period. As we had net losses for the three months ended March 31, 2026 and 2025, all potential common shares were determined to be anti-dilutive during those periods.

The following table sets forth the computation of net loss per common share:

The total numbers of securities that could potentially dilute net income per share in the future that were not considered in the diluted net loss per share calculations because the effect would have been anti-dilutive were as follows:

NOTE 14. COMMITMENTS AND CONTINGENCIES

On December 7, 2021 and March 29, 2022, two verified shareholder derivative lawsuits were filed in the U.S. District Court for the Northern District of California purportedly on behalf of Ardelyx against certain of Ardelyx’s executive officers and members of our board of directors, captioned Go v. Raab, et al., Case No. 4:21-cv-09455-HSG, and Morris v. Raab, et al., Case No. 4:22-cv-01988-JSC (together, the Go and Morris actions). The complaints allege that the defendants’ violations of Section 14(a) of the Exchange Act, breaches of fiduciary duties, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets for personally making and/or causing Ardelyx to make materially false and misleading statements regarding the Company’s business, operations and prospects. The complaint seeks contribution under Sections 10(b) and 21D of the Exchange Act fromtwo executive officers. On January 19, 2022 and April 27, 2022, the court granted the parties’ stipulation to stay the Go and Morris actions, respectively, until resolution of the motion(s) to dismiss in the lawsuits captioned Strezsak v. Ardelyx, Inc., et al., Case No. 4:21-cv-05868-HSG and Siegel v. Ardelyx, Inc., et al., Case No. 5:21-cv-06228-HSG (together, the Securities Class Actions). On October 25, 2022, the parties filed a stipulation to consolidate and stay the Go and Morris actions, and on October 27, 2022, the court consolidated the Go and Morris actions and stayed the consolidated action pending resolution of the anticipated motion(s) to dismiss in the Securities Class Action. The Securities Class Actions were voluntarily dismissed on March 5, 2025. The court dismissed the Go and Morris actions on April 30, 2025.

On July 17, 2024, in partnership with the AAKP and the NMQF, we filed a lawsuit in the U.S. District Court for the District of Columbia against CMS, claiming that CMS has violated its statutory and regulatory authority under MIPPA, which established the ESRD PPS bundled payment system for dialysis services in 2008. Specifically, the lawsuit claims that moving XPHOZAH, along with all oral-only drugs, into the ESRD PPS is inconsistent with MIPPA’s statutory provision, and contradicts CMS’s own regulations. XPHOZAH and other oral-only drugs are not administered by dialysis providers and cannot be taken during the delivery of maintenance dialysis. On November 8, 2024, the U.S. District Court for the District of Columbia granted defendants’ Motion to Dismiss and denied plaintiffs’ Motion for Preliminary Injunction, or in the Alternative, for Expedited Summary Judgment. Following the District Court’s denial of plaintiffs’ Motion to Alter or Amend the Judgment, or in the Alternative, for an Injunction Pending Appeal, plaintiffs filed an Emergency Motion for an Administrative Stay and Injunction Pending Appeal, which was denied by the United States Court of Appeals for the District of Columbia Circuit. Appellants filed an initial brief in the appeal on February 4, 2025; Appellees filed an initial brief on March 6, 2025; and Appellants filed a reply brief on March 27, 2025. Both Appellees and Appellants filed a final brief on April 10, 2025. Oral argument in the case was heard on September 25, 2025.

On August 16, 2024, a complaint was filed against us in the U.S. District Court of Massachusetts, captioned Yarborough v. Ardelyx, Inc., et al., No. 24-cv-12119 (D. Mass.). The complaint names the Company, Michael Raab, and Justin Renz as defendants and alleges violations of Sections 10(b) and 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder, related to our announcement on July 2, 2024 that it had chosen not to file an application for Transitional Drug Add-on Payment Adjustment for XPHOZAH (the Yarborough Action). The plaintiffs seek damages and interest, and an award of costs, including attorneys’ fees. The Court appointed Tate Wood as lead plaintiff on October 30, 2024. The lead plaintiff filed an amended complaint on January 13, 2025, in which he added Susan Rodriguez, Laura Williams and Elizabeth Grammer as additional defendants and removed Justin Renz as a defendant. The lead plaintiff purports to bring claims on behalf of all those who acquired Ardelyx common stock between February 22, 2024 and July 1, 2024. Defendants filed a motion to dismiss the amended complaint on March 14, 2025. Plaintiffs filed a response on May 13, 2025. Defendants filed a reply in support of their motion to dismiss on June 23, 2025. A hearing on the motion to dismiss was held on September 25, 2025, and on December 24, 2025, the Court granted defendants’ motion to dismiss and issued an order dismissing the case with prejudice. On January 21, 2026, Plaintiffs appealed the District Court’s decisions to the United States Court of Appeals for the First Circuit. On March 26, 2026, the Court granted the Parties’ stipulated voluntary dismissal of Plaintiffs’ appeal.

On September 6 and 13, 2024, certain Ardelyx shareholders filedtwo verified derivative complaints purportedly on behalf of the Company in the United States District Court for the District of Massachusetts alleging violations of Sections 10(b) and/or 14(a) of the Exchange Act, breaches of fiduciary duty, unjust enrichment, waste, and aiding and abetting breaches of fiduciary duty against certain members of our board of directors and management based on substantially the same factual allegations in the Yarborough Action. The complaints seek unspecified damages and corporate governance reforms, as well as costs and attorneys’ fees. On September 25, 2024, the Court consolidated thetwo derivative actions into the case In re Ardelyx, Inc. Stockholder Derivative Litigation, Case No. 1:24-cv-12302-LTS (D. Mass.). On November 7, 2024, the Court stayed the consolidated derivative action pending resolution of any and all motion(s) to dismiss in the Yarborough Action. On April 9, 2026, the Court dismissed the consolidated derivative action pursuant to the parties’ stipulation of dismissal.

From time to time, we may be involved in legal proceedings arising in the ordinary course of business. As of March 31, 2026, there is no litigation pending that would reasonably be expected to have a material adverse effect on our results of operations and financial condition.

NOTE 15. SUBSEQUENT EVENTS

On April 28, 2026, we entered into an amendment to our 2022 Loan Agreement (the Sixth Amendment), by and among the Company, as borrower, SLR, as collateral agent and the lenders party thereto. Pursuant to the Sixth Amendment, among other things, (i) a portion of $200.0 million in outstanding principal previously allocated among the outstanding Term A through C Loans (collectively, the Revised Loans) was refinanced with a new Term H Loan; (ii) the maturity date for the Revised Loans has been extended from July 1, 2028 to July 1, 2030 (the New Maturity Date), which is the maturity date applicable for each other term loan; (iii) the interest-only payment period for the Revised Loans has been extended until the New Maturity Date; (iv) the interest rates for the Revised Loans, the Term H Loan, and the Term F and Term G Loans will have a collectively reduced interest rate, at the sum of 4.55% plus the greater of (a) the 1-month SOFR reference rate or (b)3.5%; (v) the Company will retain the option to draw the Term F and Term G Loans, each in the amount of $50.0 million, at the Company’s election by June 30, 2026 and December 20, 2026, respectively; and (vi) certain negative covenants and other conditions were amended to provide additional flexibility to the Company.

On the closing date of the Sixth Amendment, the Company paid approximately $1.9 million in final fees and prepayment fees in connection with the partial paydown of the Term A through C Loans.

The Company is obligated to pay a final fee with respect to each of the outstanding amounts under each of the term loans, upon the earliest to occur of (i) the New Maturity Date, (ii) the acceleration of the applicable term loan or (iii) the prepayment, refinancing, substitution or replacement of the applicable term loan. This final fee is 4.95% for the Term A through E loans,3.45% for the Term F and Term G Loans and 2.50% for the new Term H Loan.