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Atea Pharmaceuticals, Inc.

For the period ended Mar 31, 2026. Filed May 12, 2026.

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About this filing

A company's report for each of its first three quarters. The financial statements are not audited. It shows how the business has moved since the last annual report, and what management says changed.

Mar 31, 2026 · Filed May 12, 2026

AVIR$4.31+2.1%Stored close · as of Nov 6, 2026

What changed in Management’s Discussion and Analysis?

Read the current filing

Previous report: 10-Q

Period ended 2025-09-30; filed 2025-11-12.

0001193125-25-277815

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Current report: 10-Q

Period ended 2026-03-31; filed 2026-05-12.

0001193125-26-219678

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The baseline is this issuer’s latest earlier reporting period of the same form that was filed before the current report. A previous 10-Q is a different quarter, not a year-over-year comparison. Amendments are excluded.

Compared 126 previous paragraphs and 118 current paragraphs.

48 unchanged; 43 reworded; 27 added; 31 removed; 4 previous and 0 current paragraphs rearranged.

Tables are not compared: 4 previous and 3 current tables excluded. Dates, whitespace, punctuation and numbering changes are ignored; changes to financial figures remain significant.

A changed paragraph is not evidence that risk increased or decreased. An unchanged paragraph does not establish that risk stayed the same.

Added paragraphs (27)

Current report

We are a late-stage clinical biopharmaceutical company leveraging our deep understanding of antiviral drug development, medicinal chemistry, biochemistry and virology to discover, develop and commercialize novel, orally administered antivirals to treat serious viral diseases. Our current product candidate pipeline includes the regimen of bemnifosbuvir and ruzasvir which we believe has the potential to improve the current standard of care (“SOC”) for the treatment of patients with hepatitis C virus (“HCV”) infection and AT-587 which we believe has the potential to be the first direct-acting antiviral (“DAA”) for the treatment of patients, particularly immunocompromised patients, with chronic hepatitis E virus (“HEV”) infection.

Current report

C-BEYOND is fully enrolled with over 880 patients, and we expect to report topline results mid-2026. We anticipate completing enrollment of an additional 880 patients in C-FORWARD in mid-2026 and reporting topline C-FORWARD results at year-end 2026. Pending successful results from these Phase 3 clinical trials, we are targeting submission to the US Food and Drug Administration (“FDA”) of a New Drug Application (“NDA”) for marketing approval in March 2027.

Current report

We are executing a focused chemistry, manufacturing and controls (“CMC”) strategy to provide fixed dose combination (“FDC”) tablets for the completion of the Phase 3 program, to fulfill NDA requirements and to prepare us for potential launch with sufficient commercial supply for projected initial sales if the regimen of bemnifosbuvir and ruzasvir is approved for marketing.

Current report

We are developing AT-587 for the treatment of chronic HEV infection in immunocompromised patients. In this high-risk patient population, infection with HEV can rapidly progress to cirrhosis and other serious complications.

Current report

There are no DAAs currently available for the treatment of HEV. The most frequent interventions include reduction of immunosuppressive agents which, in solid organ transplant recipients, increases risk of transplant rejection, or off-label treatment with ribavirin which is indicated for treatment of other viruses but hindered by serious adverse events and limited HEV efficacy. The severity of disease in high-risk patients combined with the lack of approved HEV therapies is a substantial unmet medical need which we believe can be addressed if AT-587 is successfully developed.

Current report

AT-587 has demonstrated potent nanomolar antiviral activity against HEVin vitro. In single-dosein vivo nonclinical pharmacokinetic studies, high plasma concentrations of the surrogate to the active intracellular triphosphate metabolite were observed in all animal species tested. Results fromin vitro toxicology, pharmacology and drug metabolism and pharmacokinetic studies indicate the potential for a favorable clinical profile for AT-587. Currently, we anticipate initiating clinical development of AT-587 with a first-in-human Phase 1 study in mid-2026.

Current report

Developing a treatment for HEV, particularly a product candidate derived from our proprietary platform, is a potentially important and advantageous strategic expansion of our antiviral pipeline. If both product candidates are successfully developed and approved, we will have a hepatology portfolio that we anticipate will improve upon the current SOC for HCV and introduce the first DAA for HEV.

Current report

We have an extensive library of compounds that have been designed and generated by our medicinal chemists. Currently, we are evaluating select compounds derived from this library inin vitroand in vivo studies to assess the antiviral activity and other properties of such compounds against other RNA viral infections.

Current report

In all our discovery and preclinical efforts, we assess where there is a compelling market opportunity and then we aim to identify and advance only those candidates that we believe may have first- or best-in-class profiles with the potential to either become the SOC, or disrupt the existing SOC, and in each case, dramatically improve patient outcomes.

Current report

We remain focused on identifying initiatives, investments and opportunities to maximize stockholder value.

Current report

Additionally, in April 2025, our Board authorized a program to repurchase shares of our common stock (“Common Stock”). Under this authorization, we returned capital to our stockholders while maintaining the capacity to complete the Phase 3 clinical development of the regimen of bemnifosbuvir and ruzasvir and execute on our other strategic business plans. Under the share repurchase program, which was fully completed in 2025, we expended $25.5 million (including transaction costs and excise taxes) in connection with the repurchase of 7,673,792 shares of our Common Stock.

Current report

As of March 31, 2026, we had cash and investments of $256.0 million. Net cash used in operating activities was $46.4 million for the three months ended March 31, 2026.

Current report

Based on our current plans, we anticipate our existing financial resources will allow us to advance our current and planned clinical programs to and through key inflection points, prepare and submit an application for marketing approval of the regimen of bemnifosbuvir and ruzasvir, engage in pre-launch activities including the manufacture of the regimen of bemnifosbuvir and ruzasvir in commercial quantities sufficient to meet our initial sales projections and advance to late-stage clinical development of AT-587 for the treatment of HEV.

Current report

complete the Phase 3 clinical development of the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV;

Current report

initiate clinical development of AT-587 for the treatment of chronic HEV;

Current report

Early stage discovery activities include assessing the antiviral activity, pharmacokinetics, toxicity and other properties of select compounds derived from our nucleos(t)ide library in an effort to identify promising potential product candidates for the treatment of RNA viral infections for which there is no currently approved DAA or for which we believe the current SOC can be improved to address unmet medical needs.

Current report

the outcome of our search for strategic collaborations to strengthen our capabilities to commercialize the regimen of bemnifosbuvir and ruzasvir, if approved;
Removed paragraphs (31)

Previous report

We are a clinical-stage biopharmaceutical company leveraging our deep understanding of antiviral drug development, medicinal chemistry, biology, biochemistry and virology to discover and develop novel orally administered product candidates to treat serious viral diseases. Our lead product candidate is the regimen consisting of bemnifosbuvir and ruzasvir, which we are developing for the treatment of hepatitis C virus (“HCV”) infection. Currently, we are evaluating the regimen in a Phase 3 clinical development program which includes two Phase 3 clinical trials namely “C-Beyond” which is the clinical trial we are conducting in the United States (“US”) and Canada and “C-Forward” which is the clinical trial we are conducting outside of North America. Patient enrollment in C-Beyond and C-Forward began in April and June 2025, respectively, and is currently ongoing.

Previous report

HCV is a blood-borne, positive-sense, single-stranded ribonucleic acid ("RNA") virus that primarily infects liver cells. HCV is a leading cause of chronic liver disease, liver transplants and liver cancer in the US, Europe and Japan.

Previous report

Despite the availability of direct-acting antiviral (“DAA”) oral combination treatment regimens and eradication efforts by the World Health Organization and others, HCV continues to be a serious viral disease. An estimated 50 million people globally live with chronic HCV infection, with approximately 1 million new infections occurring each year. It is estimated that HCV leads to 240,000 deaths per year. These deaths are primarily attributable to cirrhosis and hepatocellular cancer, each of which are serious long-term consequences resulting from prolonged exposure to HCV infection.

Previous report

In the US, it is estimated that there are between 2.4 and 4.0 million persons infected with untreated HCV. Further it is reported that on an annual basis in the US, there are greater than 160,000 newly reported HCV infections. This incidence of newly reported infections outpaces substantially stagnant rates of treatment.

Previous report

In the US and elsewhere, HCV is increasingly affecting younger people, with high case rates among those between 20 to 49 years of age. Since recently infected and younger patient populations are less likely to have developed cirrhosis given the relatively shorter cumulative exposure to the virus, there has been a trend in the US of decreasing incidence of cirrhosis among individuals with HCV infection. It is estimated that less than 10% of the HCV-infected population in the US has cirrhosis.

Previous report

Each of C-Beyond and C-Forward is expected to enroll approximately 880 treatment-naïve patients, both with and without compensated cirrhosis. Patients are being stratified by genotype and cirrhosis status, and patients with human immunodeficiency virus (“HIV”) co-infection may be enrolled. For non-cirrhotic patients, eight weeks of treatment with the regimen of bemnifosbuvir and ruzasvir will be compared to 12 weeks of sofosbuvir and velpatasvir. For cirrhotic patients, 12 weeks of bemnifosbuvir and ruzasvir will be compared to 12 weeks of sofosbuvir and velpatasvir. The global geographic footprint of the Phase 3 program is to assist us in enrolling patients with varied HCV genotypes.

Previous report

In December 2024, we announced that the global Phase 2 study evaluating the regimen of bemnifosbuvir and ruzasvir had met its primary endpoints of safety and sustained virologic response (“SVR”) at 12 weeks post treatment (“SVR12”). The regimen of bemnifosbuvir and ruzasvir was generally well-tolerated with no drug-related serious adverse events (“SAEs”) or treatment discontinuations.

Previous report

Primary efficacy endpoint results showed a 98% (208/213) SVR12 rate in the per-protocol treatment adherent patient population after eight weeks of treatment with the regimen. The efficacy evaluable patient population, which included 17% treatment non-adherent patients, achieved a 95% (242/256) SVR12 rate. Additional results from the Phase 2 study showed in treatment adherent patients who were non-cirrhotic and infected with genotypes 1-4, an SVR12 rate of 99% (178/179) was achieved, demonstrating pan-genotypic potency. Treatment adherent patients with cirrhosis achieved an 88% (30/34) SVR12 rate. Although viral kinetics were slower in cirrhotic patients, all cirrhotic patients (100%; 34/34) achieved an end of treatment response at Week 8.

Previous report

The global Phase 2 study enrolled 275 HCV treatment-naïve patients, both with and without compensated cirrhosis. The study was designed to evaluate the safety and efficacy of eight weeks of treatment with the regimen consisting of once-daily bemnifosbuvir 550 mg and ruzasvir 180 mg. The primary endpoints were safety and SVR12 in the per-protocol treatment adherent population. Secondary and other endpoints included SVR12 in the efficacy evaluable population (a broader analysis population which included treatment non-adherent patients), SVR at 24 weeks post treatment (“SVR24”), virologic failure and resistance.

Previous report

The Phase 2 study results were presented in May 2025 at the European Association for the Study of Liver (“EASL”) Congress 2025. Additionally, at EASL in May 2025, we presented results from three Phase 1 studies. These studies included a pharmacokinetic study, a drug-drug interaction study and a renal impairment study.

Previous report

The results from the Phase 1 pharmacokinetic study, which evaluated a single 550 mg dose of bemnifosbuvir in healthy participants with varying degrees of hepatic impairment, support the administration of bemnifosbuvir without dose adjustment in patients with hepatic impairment. The results from the Phase 1 drug-drug interaction study in healthy participants showed that co-administration of bemnifosbuvir and ruzasvir with the standard HIV regimen bictegravir/emtricitabine/tenofovir alafenamide (B/FTC/TAF) resulted in no clinically significant pharmacokinetic changes. The results from the Phase 1 renal impairment study in healthy participants showed that a single 550 mg dose of bemnifosbuvir was well-tolerated across participants with normal kidney function, moderate-to-severe renal impairment, and those with end-stage renal disease on hemodialysis. These data suggest bemnifosbuvir may be administered without dose adjustment in patients with renal dysfunction, including those undergoing dialysis.

Previous report

In September 2024 we announced the outcome of the global Phase 3 SUNRISE-3 trial evaluating bemnifosbuvir versus placebo for the treatment of Coronavirus Disease 2019 ("COVID-19"). The trial did not meet the primary endpoint of a statistically significant reduction in all-cause hospitalization or death through Day 29 in the monotherapy cohort of 2,221 high-risk patients with mild to moderate COVID-19. We believe that the unfavorable results from this study were impacted by the constantly evolving variants of COVID-19 and rapidly changing natural history of the disease, which during the study period trended toward a milder disease. This led us to discontinue efforts to develop bemnifosbuvir for the treatment of COVID-19. In SUNRISE-3, bemnifosbuvir was generally safe and well tolerated. In April 2025, we completed the close out of the study.

Previous report

Separately, we are engaged in efforts to discover product candidates for the treatment of other diseases resulting from infection with single stranded RNA viruses. Currently, we are focusing these efforts on the discovery of a product candidate for the treatment of hepatitis E virus (“HEV”) infection.

Previous report

HEV is a positive-sense, single-stranded RNA virus that primarily infects liver cells. Transmitted via the fecal-oral route, waterborne transmission of HEV genotypes 1 and 2 causes acute epidemics in developing countries, while foodborne transmission of HEV genotypes 3 (“GT-3”) and 4 (“GT-4”) causes chronic infection in immunocompromised people in developed countries. According to the World Health Organization (“WHO”), there are an estimated 20 million new HEV infections annually, resulting in an estimated 3 million symptomatic cases and an estimated 70,000 HEV-related deaths. While HEV infection is self-limiting in certain patient populations, other patient populations, particularly those with compromised immunity, including solid organ transplant recipients, hematopoietic stem cell transplant recipients, patients with hematologic malignancies and patients with pre-existing liver disease, are at risk of rapid progression to cirrhosis. Despite the growing number of patients in high-risk populations in the US and European Union, there is currently no approved antiviral therapy available for the treatment of HEV. The treatment currently used is indicated for the treatment of other viruses andposes challenges including safety concerns and limited HEV efficacy. We expect our initial clinical efforts will focus on developing a product candidate for the potential treatment of immunocompromised patients with HEV GT-3 and GT-4 infections.

Previous report

Additionally, we are engaged in efforts to screen compounds which are a part of our compound library to assess antiviral activity against other RNA viral infections. Each of these efforts are at early stages and no clinical candidates have yet to be nominated.

Previous report

The Company continues to focus on options to maximize stockholder value.

Previous report

In April 2025, our Board of Directors (“Board”) authorized the repurchase of up to $25.0 million of our common stock (“Share Repurchase Program). The repurchase of shares under the Share Repurchase Program has been completed. Under the Share Repurchase Program, we repurchased an aggregate of 7,673,793 shares of common stock through open market and privately negotiated transactions, including 3,054,195 shares purchased during the three months ended September 30, 2025. The aggregate price of the shares repurchased during such three month period was $11.4 million (including transaction costs and excise taxes). All repurchased shares were retired immediately upon receipt and returned to authorized and unissued status.

Previous report

As of September 30, 2025, we had cash, cash equivalents and marketable securities of $329.3 million. Net cash used in operating activities was $103.8 million for the nine months ended September 30, 2025. In an effort to enhance efficiency in the management of infrastructure expenses, in the first quarter of 2025, we reduced our workforce by approximately 25%. This workforce reduction is expected to result in aggregate cost savings of approximately $15 million through 2027. As noted above, in April 2025, our Board authorized the Share Repurchase Program. This authorization reflects our commitment to return capital to our stockholders while maintaining the capacity to complete our Phase 3 clinical development of the regimen of bemnifosbuvir and ruzasvir and execute on our strategic business plans. Based on our current plans, we anticipate our existing financial resources, will allow us to advance our current and planned clinical programs to and through key inflection points including the completion of clinical development of the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV.

Previous report

conduct Phase 3 clinical development of the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV which includes the purchase of comparator drug;

Previous report

initiate clinical development of product candidates for the treatment of respiratory and other diseases resulting from infection with single stranded RNA viruses;

Previous report

On July 4, 2025, the US enacted the budget reconciliation bill H.R. 1 into law, which included significant changes to US income tax laws. Provisions in the law impacting corporate tax matters include the restoration of 100% bonus depreciation, potential for immediate expensing for domestic research and experimental expenditures, changes to Section 163(j) interest limitations, modifications to the US’s international tax framework, and expanded Section 162(m) aggregation requirements. The impact of these changes is not expected to have a material effect on our future results of operations.

Previous report

Comparison of the Nine Months Ended September 30, 2025 and 2024

Previous report

Research and development expenses decreased by $18.2 million from $118.4 million for the nine months ended September 30, 2024 to $100.2 million for the nine months ended September 30, 2025. The net decrease was primarily driven by lower external spend as our COVID-19 Phase 3 SUNRISE-3 clinical trial was completed in 2024. The decrease was partially offset by an increase in external spend for our HCV Phase 3 clinical development including the purchase of comparator drug and expense related to the Merck milestone. Additionally, lower internal research and development expenses were primarily related to a decrease in stock-based compensation and payroll related expense in the nine months ended September 30, 2025.

Previous report

General and administrative expenses decreased by $9.7 million from $35.5 million for the nine months ended September 30, 2024 to $25.7 million for the nine months ended September 30, 2025. The net decrease was primarily related to lower stock-based compensation expense, partially offset by increased professional fees.

Previous report

Income tax expense was $0.6 million and $0.7 million for the nine months ended September 30, 2025 and 2024, respectively.
Reworded paragraphs (43)

Previous wording

The objective of our HCV development program, which is now enrolling patients in two Phase 3 clinical trials, is to improve upon the current standard of care ("SOC") by offering, the regimen of bemnifosbuvir and ruzasvir, if successfully developed and approved, as a differentiated pan-genotypic protease inhibitor-free therapeutic for HCV-infected patients, many of whom take medications for other conditions. We believe that a novel treatment, with a profile that can be easily prescribed for and administered to today’s population of HCV-infected patients (e.g. young, newly infected, non-cirrhotic) would be a significant improvement to the current SOC.

Current wording

The objective of our HCV development program is to improve upon the current SOC by offering bemnifosbuvir and ruzasvir as a differentiated pan-genotypic protease inhibitor-free, short-duration regimen for patients infected with HCV, if successfully developed and approved. We believe that a novel treatment regimen that can be easily prescribed will benefit today’s HCV population, which is predominately young (20-49 years old) and non-cirrhotic, and it would be a significant improvement to the current SOC.

Previous wording

Presently, there are no short-course (i.e., eight week) nucleoside inhibitor-based, pan-genotypic HCV treatment regimens. Results from the clinical and nonclinical studies we have conducted to date, including a global Phase 2 clinical trial which enrolled 275 HCV infected patients, have shown that the regimen of bemnifosbuvir and ruzasvir offers high potency, a low risk for drug-drug interactions, good tolerability and convenience in that it can be taken with or without food which we believe would offer a significant improvement to the current SOC, if approved.

Current wording

Presently, there are no short-course (i.e., eight week) nucleotide inhibitor-based, pan-genotypic HCV treatment regimens. Clinical and nonclinical results from studies conducted to date, including a global Phase 2 clinical trial which enrolled 275 HCV infected patients, have shown that the regimen of bemnifosbuvir and ruzasvir has high potency and has been well tolerated. These studies have also shown that the regimen has a low risk for drug-drug interactions with many commonly prescribed medications including proton pump inhibitors and offers the convenience of being able to be taken with or without food. This is a profile that we believe will offer a significant improvement to the current SOC, if approved.

Previous wording

The global HCV Phase 3 program we are currently conducting includes two randomized, open label Phase 3 trials comparing the regimen of bemnifosbuvir and ruzasvir to sofosbuvir and velpatasvir in patients with chronic HCV infection. The overall clinical trial design is identical for each trial. The Phase 3 trial being conducted in the US and Canada is referred to as C-Beyond and the Phase 3 clinical trial being conducted outside of North America is referred to as C-Forward.

Current wording

The global HCV Phase 3 program we are conducting consists of two randomized, open label studies: C-BEYOND which has clinical trial sites in the United States (“US”) and Canada, and C-FORWARD which has clinical trial sites in countries outside of North America. In these Phase 3 trials we are comparing our regimen of bemnifosbuvir and ruzasvir to an active comparator, the regimen of sofosbuvir and velpatasvir, in patients with chronic HCV infection. We are conducting the Phase 3 program in geographically diverse regions in order to enroll patients with a broad array of HCV genotypes.

Previous wording

In 2024, global net sales of branded HCV therapeutics known in the US as Epclusa® and Mavyret® together with the authorized generic copies of Epclusa exceeded $2.9 billion with the US contributing approximately 50% of these sales. Given the large number of patients currently infected with HCV and high rates of annual incidence, it is expected that a substantial global market will exist for the foreseeable future.

Current wording

Given the large number of patients currently infected with HCV, which is reported by the US Center for Disease Control and Prevention to be as many as four million persons in the US, and the incidence of newly reported chronic infections continuing to outpace rates of treatment, we expect that a substantial global market will exist for the foreseeable future. In 2025, global net sales of branded HCV therapeutics known in the US as Epclusa®(including the authorized generic copy of Epclusa) and Mavyret®exceeded $2.5 billion with the US accounting for approximately 50% of these sales.

Previous wording

We believe we are well capitalized to advance our current programs. We had $329.3 million in cash, cash equivalents and marketable securities at September 30, 2025.

Current wording

We believe we are well capitalized to advance our current programs. We had $256.0 million in cash, cash equivalents and marketable securities at March 31, 2026.

Previous wording

Given that the Company believes the HCV Phase 3 clinical development results will drive stockholder value and catalyze business development discussions, the Company has concluded its formal engagement with Evercore LLC, a global independent investment bank. We remain open to consideration of all opportunities to drive stockholder value including strategic transactions.

Current wording

Expecting that the results of our HCV Phase 3 clinical development program, if successful, will drive stockholder value and catalyze business development discussions, in November 2025, we concluded the formal engagement to explore strategic partnerships which we previously entered into with Evercore LLC, a global independent investment bank. Currently, we expect to report topline results from our Phase 3 C-Beyond trial in mid-2026 and topline results from our Phase 3 C-Forward trial at year-end 2026. We remain open to consideration of strategic transactions and all other opportunities to drive stockholder value.

Previous wording

In addition to a non-refundable upfront payment that we made in February 2022, we are required to pay Merck milestone payments upon our achievement of certain development, regulatory and sales-based milestones. Additionally, we will pay Merck tiered royalties based on annual net sales of Products ranging from high single digits to mid-teens percentages. Our royalty payment obligations will continue until the later of (i) the expiration of the last to expire valid claim of a licensed Merck patent claiming such Product and (ii) a period of years after the first commercial sale of such Product in such country. We may terminate the Merck License Agreement for convenience upon prior written notice. The first milestone in the amount of $5.0 million became due and payable when we enrolled our first patient in C-BEYOND, the Phase 3 clinical trial that we are currently conducting in the US and Canada evaluating the regimen of bemnifosbuvir and ruzasvir. The Company recognized this milestone payment as research and development expense in the three months ended June 30, 2025. The next potential milestone, in the amount of $10.0 million, is payable upon acceptance by the FDA of a new drug application covering a product candidate including ruzasvir which we currently anticipate will be the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV.

Current wording

In addition to a non-refundable upfront payment that we made in February 2022, we agreed to pay Merck milestone payments upon our achievement of certain development, regulatory and sales-based milestones. Additionally, we will pay Merck tiered royalties based on annual net sales of Products ranging from high single digits to mid-teens percentages. Our royalty payment obligations will continue until the later of (i) the expiration of the last to expire valid claim of a licensed Merck patent claiming such Product and (ii) a period of years after the first commercial sale of such Product in such country. We may terminate the Merck License Agreement for convenience upon prior written notice. The first milestone in the amount of $5.0 million became due and payable in April 2025 when we enrolled our first patient in C-BEYOND, the Phase 3 clinical trial that we are currently conducting in the US and Canada evaluating the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV. The Company recognized this milestone payment as research and development expense in the three months ended June 30, 2025. The next potential milestone, in the amount of $10.0 million, is payable upon acceptance by the FDA of a new drug application covering a product candidate including ruzasvir. If we successfully complete the ongoing HCV Phase 3 clinical trials evaluating the regimen of bemnifosbuvir and ruzasvir and are able to complete and submit the NDA to the FDA on our current projected timeline, we anticipate that this next potential milestone may become due and payable during the three months ended June 30, 2027.

Previous wording

We expect that our net cash used in operating activities will remain significant as we advance our HCV product candidate through preclinical and clinical development, seek regulatory approval, and prepare for and, if approved, manufacture such product at commercial scale and otherwise pursue commercialization activities; acquire, discover, validate and develop additional product candidates; obtain, maintain, protect and enforce our intellectual property portfolio; and, if necessary, hire additional personnel. In addition, we may incur additional costs as we continue to operate as a public company. We believe that our available cash, cash equivalents and marketable securities will be sufficient to fund our planned operations through 2027. We have based this estimate on assumptions that may prove to be wrong and we could exhaust our available capital resources sooner than we expect.

Current wording

We expect that our net cash used in operating activities will remain significant as we complete the clinical development of the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV, seek regulatory approval, manufacture such product at commercial scale and prepare for and, if approved, pursue commercialization activities; advance AT-587, our HEV product candidate through preclinical and clinical development; acquire, discover, validate and develop additional product candidates; obtain, maintain, protect and enforce our intellectual property portfolio; and, if necessary, hire additional personnel. In addition, we may incur additional costs as we continue to operate as a public company. We believe that our available cash, cash equivalents and marketable securities will be sufficient to fund our planned operations through 2027. We have based this estimate on assumptions that may prove to be wrong and we could exhaust our available capital resources sooner than we expect.

Previous wording

We do not have any products approved for sale and have not generated any product revenue since inception. We do not anticipate generating any revenue from product sales for the foreseeable future. Our ability to generate product revenue will depend on the successful development, regulatory approval and eventual commercialization of one or more of our product candidates. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through private or public equity or debt financings, collaborative or other arrangements with third parties, or through other sources of financing. Our failure to meet the primary endpoint of our COVID-19 SUNRISE-3 Phase 3 clinical trial may make such financing more difficult. Adequate funding may not be available to us on acceptable terms, or at all. If we fail to raise capital or enter into such agreements as and when needed, we may have to significantly delay, scale back or discontinue the development and commercialization of our product candidates.

Current wording

We do not have any products approved for sale and have not generated any product revenue since inception. We do not anticipate generating any revenue from product sales for the foreseeable future. Our ability to generate product revenue will depend on the successful development, regulatory approval and eventual commercialization of one or more of our product candidates. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through private or public equity or debt financings, collaborative or other arrangements with third parties, or through other sources of financing. Adequate funding may not be available to us on acceptable terms, or at all. If we fail to raise capital or enter into such agreements as and when needed, we may have to significantly delay, scale back or discontinue the development and commercialization of our product candidates.

Previous wording

complete non-clinical NDA enabling activities, including those associated with the manufacture of the regimen of bemnifosbuvir and ruzasvir in fixed dose combination tablets;

Current wording

complete non-clinical NDA enabling activities, including those associated with the manufacture of the regimen of bemnifosbuvir and ruzasvir at commercial scale;

Previous wording

seek market approval and prepare for potential commercialization of any product candidates that we may successfully develop;

Current wording

seek marketing approval and prepare for potential commercialization of the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV;

Previous wording

continue discovery and IND-enabling activities to identify other potential product candidates for the treatment of diseases caused by hepatitis E and other single stranded RNA viruses;

Current wording

continue discovery and preclinical activities to identify other potential product candidates for the treatment of diseases caused by other single stranded RNA viruses;

Previous wording

Substantially all of our research and development expenses consist of expenses incurred in connection with the discovery and development of our product candidates. These expenses include external costs consisting of fees paid to third parties, including CROs and CMOs, to conduct certain research and development activities on our behalf, consulting costs and in the case of our HCV Phase 3 program, costs to purchase comparator drug. Research and development expenses also include internal costs consisting of payroll and personnel-related expenses, including salaries and bonuses, employee benefit costs and stock-based compensation expenses for our research and development employees and allocated overhead, including rent, equipment, depreciation, information technology costs and utilities attributable to our research and development personnel. We expense both internal and external research and development expenses as they are incurred. In circumstances where amounts have been paid in advance or in excess of costs incurred, we record a prepaid expense, which is expensed as services are performed or goods are delivered.

Current wording

Substantially all of our research and development expenses consist of expenses incurred in connection with the discovery and development of our product candidates. These expenses include external costs consisting of fees paid to third parties, including CROs and CMOs, to conduct certain research and development activities on our behalf and consulting costs, as well as internal costs consisting of payroll and personnel-related expenses, including salaries and bonuses, employee benefit costs and stock-based compensation expenses for our research and development employees and allocated overhead, including rent, equipment, depreciation, information technology costs and utilities attributable to our research and development personnel. We expense both internal and external research and development expenses as they are incurred. In circumstances where amounts have been paid in advance or in excess of costs incurred, we record a prepaid expense, which is expensed as services are performed or goods are delivered.

Previous wording

A significant portion of our research and development costs have been external costs, which we track by therapeutic area. We have not historically tracked our internal research and development expenses or early stage discovery costs by therapeutic area as they are deployed across multiple programs. Early stage discovery activities consist of assessing the antiviral activity and other properties of select compounds derived from our compound library against respiratory and other RNA viral infections.

Current wording

A significant portion of our research and development costs have been external costs, which we track by therapeutic area. We have not historically tracked our internal research and development expenses by therapeutic area as they are deployed across multiple programs.

Previous wording

Substantially all of our resources are focused on the development of our product candidates. We expect our research and development expenses to vary quarter over quarter particularly as we advance our Phase 3 HCV clinical program and prepare for the possible commercialization of the regimen of bemnifosbuvir and ruzasvir if the Phase 3 clinical development is successful. Predicting the timing or cost to complete our clinical programs, validate our commercial manufacturing and supply processes and manufacture of product at commercial scale is difficult and delays may occur because of many factors, including factors outside of our control. For example, if the FDA or other regulatory authorities were to require us to conduct clinical trials beyond those that we currently anticipate or the time to complete planned clinical trials is extended due to delays in enrollment or otherwise, we could be required to expend significant additional financial resources and time on the completion of clinical development. Furthermore, we are unable to predict with any certainty when our HCV product candidate or any other product candidate we may develop will receive regulatory approval, if ever.

Current wording

Substantially all of our resources are focused on the development of our product candidates. We expect our research and development expenses to vary quarter over quarter particularly as we complete our Phase 3 HCV clinical program, manufacture commercial launch supply for the possible commercialization of the regimen of bemnifosbuvir and ruzasvir and advance AT-587 for the treatment of HEV. Predicting the timing or cost to complete our clinical programs, validate our commercial manufacturing and supply processes and manufacture of product at commercial scale is difficult and delays may occur because of many factors, including factors outside of our control. For example, if the FDA or other regulatory authorities were to require us to conduct clinical trials beyond those that we currently anticipate or the time to complete planned clinical trials is extended due to delays in enrollment or otherwise, we could be required to expend significant additional financial resources and time on the completion of clinical development. Furthermore, we are unable to predict with any certainty when our HCV and HEV product candidates or any other product candidate we may develop will, if ever, receive regulatory approval.

Previous wording

We anticipate that our general and administrative expenses may increase, including in connection with any future expansion of our organization for potential commercialization of our product candidates, as a result of increased personnel costs, expanded infrastructure, increased consulting, legal and accounting services, costs associated with complying with The Nasdaq Global Select Market and Securities and Exchange Commission requirements and increased investor relations costs.

Current wording

We anticipate that our general and administrative expenses may increase, including in connection with any future expansion of our organization for potential commercialization of our product candidates, as a result of increased personnel costs, expanded infrastructure, increased consulting, legal and accounting services, costs associated with complying with Nasdaq and SEC requirements and increased investor relations costs.

Previous wording

Interest income and other, net consists primarily of interest income earned on our cash, cash equivalents and marketable securities.

Current wording

Interest income and other, net, consists primarily of interest income earned on our cash and investments.

Previous wording

Research and development expenses increased by $12.2 million from $26.2 million for the three months ended September 30, 2024 to $38.3 million for the three months ended September 30, 2025. The net increase was primarily driven by increased external spend related principally for our HCV Phase 3 clinical development program partially offset by substantially lower COVID-19 external spend as a result of our COVID-19 Phase 3 SUNRISE-3 clinical trial being completed in 2024 together with lower internal research and development expenses primarily related to a decrease in stock-based compensation and payroll related expenses in the three months ended September 30, 2025.

Current wording

Research and development expenses increased by $11.6 million from $29.6 million for the three months ended March 31, 2025 to $41.1 million for the three months ended March 31, 2026. The net increase was primarily driven by an increase in external spend for our HCV Phase 3 clinical development and HEV preclinical development activities. The increase was partially offset by lower internal research and development expenses primarily related to lower salaries and wages and lower stock-based compensation expense in the three months ended March 31, 2026.

Previous wording

General and administrative expenses decreased by $3.8 million from $11.0 million for the three months ended September 30, 2024 to $7.2 million for the three months ended September 30, 2025. The net decrease was primarily related to lower stock-based compensation expense.

Current wording

General and administrative expenses decreased by $2.6 million from $9.5 million for the three months ended March 31, 2025 to $6.9 million for the three months ended March 31, 2026. The net decrease was primarily related to lower salaries and wages, lower stock-based compensation expense and lower professional fees.

Previous wording

Interest income and other, net, decreased by $2.6 million for the three months ended September 30, 2025 compared to the three months ended September 30, 2024, primarily due to lower investment balances.

Current wording

Interest income and other, net, decreased by $2.4 million for the three months ended March 31, 2026 compared to the three months ended March 31, 2025, primarily due to lower investment balances.

Previous wording

Income tax expense was $0.2 million for the three months ended September 30, 2025 and 2024.

Current wording

Income tax expense was $0.1 and $0.2 million for the three months ended March 31, 2026 and 2025, respectively.

Previous wording

As of September 30, 2025, we had cash, cash equivalents and marketable securities of $329.3 million. We believe that our available cash, cash equivalents and marketable securities will be sufficient to fund our planned operations through 2027, including the completion of the Phase 3 program evaluating the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV. We have based this estimate on assumptions that may prove to be wrong and we could exhaust our available capital resources sooner than we expect.

Current wording

As of March 31, 2026, we had cash, cash equivalents and marketable securities of $256.0 million. We believe that our available cash and investments will be sufficient to fund our planned operations through 2027 including the completion of the Phase 3 program evaluating the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV. We have based this estimate on assumptions that may prove to be wrong and we could exhaust our available capital resources sooner than we expect.

Previous wording

We are party to an amended and restated open market sales agreement ("Sales Agreement") with Jefferies LLC ("Jefferies"), pursuant to which we may from time to time offer and sell shares of our common stock (“Common Stock”) for an aggregate offering price of up to $200.0 million, through or to Jefferies, acting as sales agent or principal. We have agreed to pay Jefferies a commission of up to 3.0% of the aggregate gross proceeds from each sale of shares, reimburse legal fees and disbursements and provide Jefferies with customary indemnification and contribution rights. As of September 30, 2025, no shares have been issued under the Sales

Current wording

We are party to an amended and restated open market sales agreement ("Sales Agreement") with Jefferies LLC ("Jefferies"), pursuant to which we may from time to time offer and sell shares of our Common Stock for an aggregate offering price of up to $200.0 million, through or to Jefferies, acting as sales agent or principal. We have agreed to pay Jefferies a commission of up to 3.0% of the aggregate gross proceeds from each sale of shares, reimburse legal fees and disbursements and provide Jefferies with customary indemnification and contribution rights. As of March 31, 2026, no shares have been issued under the Sales Agreement. The shares will be offered and sold under the Company's shelf registration statement on Form S-3 declared effective by the SEC on November 19, 2024.

Previous wording

To date, we have not generated any product revenue. We do not expect to generate any product revenue unless and until we obtain regulatory approval of and commercialize any of our product candidates and we do not know when, or if, this will occur. We expect to continue to incur significant expenditures for the foreseeable future as we continue the development of, and seek regulatory approvals for, our product candidates and begin to commercialize any approved products. We are subject to all of the risks typically related to the development of new product candidates, and we may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. Moreover, we expect to incur additional general and administrative costs as we continue to operate as a public company and potentially expand our organization to support the initiation of activities in preparation for potential commercialization of our product candidates.

Current wording

To date, we have not generated any product revenue. We do not expect to generate any product revenue unless and until we obtain regulatory approval of and commercialize any of our product candidates and we do not know when, or if, this will occur. We expect to continue to incur significant expenditures for the foreseeable future as we continue the development of, and seek regulatory approvals for, our product candidates, and prepare for and begin to commercialize any approved products. We are subject to all of the risks typically related to the development of new product candidates, and we may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. Moreover, we expect to incur additional general and administrative costs, including selling costs, as we continue to operate as a public company and potentially expand our organization to support and otherwise initiate additional activities in preparation for potential commercialization of the regimen of bemnifosbuvir and ruzasvir.

Previous wording

the scope, timing, rate of progress and costs of our Phase 3 program evaluating the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV and our other drug discovery efforts, preclinical development activities, laboratory testing and clinical trials for other product candidates;

Current wording

the scope, timing, rate of progress and costs of our Phase 3 program evaluating the combination of bemnifosbuvir and ruzasvir for the treatment of HCV and our other drug discovery efforts, preclinical development activities, laboratory testing and clinical trials for other product candidates including AT-587 for the treatment of HEV;

Previous wording

the number and scope of clinical programs we decide to pursue;

Current wording

the number and scope of additional clinical programs we decide to pursue;

Previous wording

the cost, timing and outcome of preparing for and undergoing regulatory review of our product candidates;

Current wording

the cost, timing and outcome of preparing for and undergoing regulatory review of our regimen of bemnifosbuvir and ruzasvir for the treatment of HCV and any other product candidates;

Previous wording

the scope and costs of development and commercial manufacturing activities which may be adversely impacted if tariffs are imposed on pharmaceutical products or the materials, including regulatory starting materials, necessary to manufacture our product candidates;

Current wording

the scope and costs of development and commercial manufacturing activities;

Previous wording

the cost and timing associated with commercializing our product candidates, if they receive marketing approval;

Current wording

the cost and timing associated with commercializing regimen of bemnifosbuvir and ruzasvir for the treatment of HCV and any other product candidates, if they receive marketing approval;

Previous wording

our efforts to enhance operational systems and our ability to attract, hire and retain qualified personnel, including personnel to support the development of our product candidates and, ultimately, the sale of our products, following regulatory approval;

Current wording

our ability to attract, hire and retain qualified personnel, including personnel to support the development of our product candidates and, if approved, the commercialization of our products;

Previous wording

our implementation of operational, financial and management systems; and

Current wording

our maintenance and enhancement of operational, financial and management systems; and

Previous wording

A change in the outcome of any of these or other variables with respect to the development of any of our product candidates could significantly change the costs and timing associated with the development of one or more of our product candidates. Furthermore, our operating plans may change in the future, and we will continue to require additional capital to meet operational needs and capital requirements associated with such operating plans. If we raise additional funds by issuing equity securities, our stockholders may experience dilution. Any future debt financing that we enter into may impose upon us additional covenants that restrict our operations, including limitations on our ability to incur liens or additional debt, pay dividends, repurchase our common stock, make certain investments or engage in certain merger, consolidation or asset sale transactions. Any debt financing or additional equity that we raise may contain terms that are not favorable to us or our stockholders.

Current wording

A change in the outcome of any of these or other variables with respect to any of our product candidates could significantly change the costs and timing associated with the development or potential commercialization of one or more of our product candidates. Furthermore, our operating plans may change in the future, and we will continue to require additional capital to meet operational needs and capital requirements associated with such operating plans. If we raise additional funds by issuing equity securities, our stockholders may experience dilution. Any future debt financing that we enter into may impose upon us additional covenants that restrict our operations, including limitations on our ability to incur liens or additional debt, pay dividends, repurchase our Common Stock, make certain investments or engage in certain merger, consolidation or asset sale transactions. Any debt financing or additional equity that we raise may contain terms that are not favorable to us or our stockholders.

Previous wording

Adequate funding may not be available to us on acceptable terms or at all. Our failure to raise capital as and when needed could have a negative impact on our financial condition and our ability to pursue our business strategies. If we are unable to raise additional funds when needed, we may be required to delay, reduce, or terminate some or all of our development programs and clinical trials or we may also be required to sell or license to others rights to our product candidates in certain territories or indications that we would prefer to develop and commercialize ourselves. If we are required to enter into collaborations and other arrangements to supplement our funds, we may have to give up certain rights that limit our ability to develop and commercialize our product candidates or may have other terms that are not favorable to us or our stockholders, which could materially affect our business and financial condition.

Current wording

Adequate funding may not be available to us on acceptable terms or at all. Our failure to raise capital as and when needed could have a negative impact on our financial condition and our ability to pursue our business strategies. If we are unable to raise additional funds when needed, we may be required to delay, reduce, or terminate some or all of our development programs, clinical trials and commercialization activities or we may also be required to sell or license to others rights to our product candidates in certain territories or indications that we would prefer to develop and commercialize ourselves. If we are required to enter into collaborations and other arrangements to supplement our funds, we may have to give up certain rights that limit our ability to develop and commercialize our product candidates or may have other terms that are not favorable to us or our stockholders, which could materially affect our business and financial condition.

Previous wording

Market volatility, inflation, interest rate fluctuations, tariffs, macroeconomic trends and geopolitical events, including civil or political unrest and terrorism, may have a significant impact on the availability of funding sources and the terms on which any funding may be available.

Current wording

Market volatility, inflation, interest rate fluctuations and other macroeconomic trends and geopolitical events, including civil or political unrest and terrorism, may have a significant impact on the availability of funding sources and the terms on which any funding may be available.

Previous wording

Net cash used in operating activities for the nine months ended September 30, 2024 was $105.1 million. Cash used in operating activities was primarily due to a net loss of $134.8 million, a decrease in accrued expenses and other current liabilities of $8.4 million and an accretion of premium and discounts on marketable securities of $9.1 million, partially offset by a stock-based compensation expense of $37.5 million, a decrease in prepaid expenses and other current assets of $8.3 million and an increase in accounts payable of $1.5 million.

Current wording

Net cash used in operating activities for the three months ended March 31, 2026 was $46.4 million. Cash used in operating activities was primarily due to a net loss of $45.4 million, accretion of premium and discounts on marketable securities of $0.6 million, a decrease in accounts payable and accrued expenses and other liabilities of $6.2 million, partially offset by stock-based compensation expense of $3.7 million and a decrease in prepaid expenses and other assets of $2.0 million.

Previous wording

Net cash used in operating activities for the nine months ended September 30, 2025 was $103.8 million. Cash used in operating activities was primarily due to a net loss of $113.5 million, accretion of premium and discounts on marketable securities of $4.1 million, increase in prepaid expenses and other current assets of $4.5 million.

Current wording

Net cash used in operating activities for the three months ended March 31, 2025 was $30.6 million. Cash used in operating activities was primarily due to a net loss of $34.3 million, accretion of premium and discounts on marketable securities of $1.7 million, and an increase in other assets of $4.2 million, partially offset by stock-based compensation expense of $7.0 million and an increase in accounts payable and accrued expenses of $3.3 million.

Previous wording

Net cash provided by investing activities for the nine months ended September 30, 2025 was $142.2 million and consisted of sales and maturities of marketable securities of $380.3 million partially offset by purchases of marketable securities of $238.1 million.

Current wording

Net cash provided by investing activities for the three months ended March 31, 2026 was $29.7 million and consisted of sales and maturities of marketable securities of $104.3 million partially offset by purchases of marketable securities of $74.5 million.

Previous wording

Net cash provided by investing activities for the nine months ended September 30, 2024 was $59.5 million and consisted of sales and maturities of marketable securities of $462.2 million offset by purchases of marketable securities of $402.7 million.

Current wording

Net cash provided by investing activities for the three months ended March 31, 2025 was $85.6 million and consisted of sales and maturities of marketable securities of $208.2 million partially offset by purchases of marketable securities of $122.6 million.

Previous wording

Net cash used in financing activities for the nine months ended September 30, 2025 was $25.7 million and consisted of stock repurchases of $25.5 million (including transaction costs and excise taxes) and net issuance of restricted stock units of $0.5 million, partially offset by $0.3 million in proceeds from the issuance of our common stock under our Employee Stock Purchase Plan (“ESPP”) and upon exercises of stock options.

Current wording

Net cash provided by financing activities for the three months ended March 31, 2026 was $0.3 million and consisted of $0.9 million in proceeds from the exercise of stock options and $0.1 million in proceeds from the issuance of our Common Stock under our employee stock purchase plan offset by $0.7 million used in connection with the net settlement of vested restricted stock units.

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Previous report — wording carried elsewhere

The following table summarizes our results of operations for the periods indicated:

Previous report — wording carried elsewhere

Interest income and other, net, decreased by $6.7 million for the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024, primarily due to lower investment balances.

Previous report — wording carried elsewhere

Agreement. Any shares will be offered and sold under the Company's shelf registration statement on Form S-3 declared effective by the SEC on November 19, 2024.

Previous report — wording carried elsewhere

partially offset by stock-based compensation of $16.1 million and an increase in accounts payable and accrued expenses of $2.0 million.