Nature of Business	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Business Overview Atea Pharmaceuticals, Inc., together with its wholly owned subsidiary, Atea Pharmaceuticals Securities Corporation, is referred to herein on a consolidated basis as “Atea” or the “Company”. The Company is a late-stage clinical biopharmaceutical company focused on discovering, developing and commercializing oral antiviral therapeutics to improve the lives of patients suffering from serious viral infections. The Company’s lead product candidate, the regimen of bemnifosbuvir, and ruzasvir, an NS5A inhibitor is currently in Phase 3 clinical development for the treatment of hepatitis C virus (“HCV”). The Company is also developing AT-587 for the treatment of hepatitis E virus ("HEV"). The Company’s global HCV Phase 3 program consists of two randomized, open label studies: C-BEYOND which has clinical trial sites in the US and Canada and C-FORWARD which has clinical trial sites in countries outside of North America. The Phase 3 trials are comparing the regimen of bemnifosbuvir and ruzasvir to an active comparator, the regimen of sofosbuvir and velapatsvir, in patients with chronic HCV. The Phase 3 program is being conducted in geographically diverse regions in an effort to enroll patients with a broad array of the HCV genotypes. C-BEYOND is fully enrolled with over 880 patients, and the Company currently expects to report topline results mid-2026. The Company is actively progressing enrollment of an additional 880 patients in C-FORWARD and currently expects to report topline results from C-FORWARD at year-end 2026. Pending successful results from the Phase 3 clinical trials, the Company is targeting submission to US Food and Drug Administration of a New Drug Application for marketing approval in March 2027. In January 2026, the Company announced that AT-587 had been selected as the HEV clinical development product candidate. Currently, the Company anticipates to initiate clinical development of AT-587 in a Phase 1 program in mid-2026. Liquidity and Capital Resources As of December 31, 2025, the Company had $301,830 in cash, cash equivalents and marketable securities, which the Company believes will be sufficient to fund its operations for a period through at least twelve months from the issuance date of these consolidated financial statements. The Company is a party to an amended and restated open market sales agreement (“Sales Agreement”) with Jefferies LLC (“Jefferies”), under which the Company may from time to time offer and sell shares of its common stock (“Common Stock”) for an aggregate offering price of up to $200,000, through or to Jefferies, acting as sales agent or principal. The shares will be offered and sold under the Company’s shelf registration statement on Form S-3 and a related prospectus declared effective by the Securities and Exchange Commission (the “SEC”) on November 19, 2024. The Company has agreed to pay Jefferies a commission of 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 December 31, 2025, no shares have been issued under the Sales Agreement. Risks and Uncertainties The Company is subject to risks and uncertainties common to late-stage clinical biopharmaceutical companies. These risks include, but are not limited to, potential failure of preclinical and clinical studies, uncertainties associated with research and development activities generally, competition from technical innovations of others, dependence upon key personnel, compliance with governmental regulations, the need to obtain marketing approval for any product candidate that the Company may develop, the need to gain broad acceptance among patients, payers and healthcare providers to successfully commercialize any product for which marketing approval is obtained and the need to secure and maintain adequate intellectual property protection for the Company’s proprietary technology and products. Further, the Company is dependent on third-party service providers for the conduct of its preclinical research, clinical development and manufacturing activities. Product candidates currently under development, including the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV, will require significant amounts of additional capital and additional research and development efforts, and all will require regulatory approval, prior to commercialization. Even if the Company is able to generate revenues from the sale of its product candidates, if any are approved and commercialized, it may not become profitable. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations. The Company may seek additional capital through one or more of a combination of financing through the sale of additional equity securities, debt financing, or funding in connection with any new collaborative relationships it may enter into or other arrangements. There can be no assurance that the Company will be able to obtain such additional funding, on terms acceptable to the Company, on a timely basis or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s existing stockholders. The Company’s cost of financing and its access to potential sources of future liquidity may be adversely impacted by a number of factors, including, without limitation, then current geopolitical events and the conditions in the financial markets including market volatility and rates of interest and inflation.

Nature of Business

12 Months Ended

Dec. 31, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Nature of Business

Business Overview

Atea Pharmaceuticals, Inc., together with its wholly owned subsidiary, Atea Pharmaceuticals Securities Corporation, is referred to herein on a consolidated basis as “Atea” or the “Company”.

The Company is a late-stage clinical biopharmaceutical company focused on discovering, developing and commercializing oral antiviral therapeutics to improve the lives of patients suffering from serious viral infections. The Company’s lead product candidate, the regimen of bemnifosbuvir, and ruzasvir, an NS5A inhibitor is currently in Phase 3 clinical development for the treatment of hepatitis C virus (“HCV”). The Company is also developing AT-587 for the treatment of hepatitis E virus ("HEV").

The Company’s global HCV Phase 3 program consists of two randomized, open label studies: C-BEYOND which has clinical trial sites in the US and Canada and C-FORWARD which has clinical trial sites in countries outside of North America. The Phase 3 trials are comparing the regimen of bemnifosbuvir and ruzasvir to an active comparator, the regimen of sofosbuvir and velapatsvir, in patients with chronic HCV. The Phase 3 program is being conducted in geographically diverse regions in an effort to enroll patients with a broad array of the HCV genotypes.

C-BEYOND is fully enrolled with over 880 patients, and the Company currently expects to report topline results mid-2026. The Company is actively progressing enrollment of an additional 880 patients in C-FORWARD and currently expects to report topline results from C-FORWARD at year-end 2026. Pending successful results from the Phase 3 clinical trials, the Company is targeting submission to US Food and Drug Administration of a New Drug Application for marketing approval in March 2027.

In January 2026, the Company announced that AT-587 had been selected as the HEV clinical development product candidate. Currently, the Company anticipates to initiate clinical development of AT-587 in a Phase 1 program in mid-2026.

Liquidity and Capital Resources

As of December 31, 2025, the Company had $301,830 in cash, cash equivalents and marketable securities, which the Company believes will be sufficient to fund its operations for a period through at least twelve months from the issuance date of these consolidated financial statements.

The Company is a party to an amended and restated open market sales agreement (“Sales Agreement”) with Jefferies LLC (“Jefferies”), under which the Company may from time to time offer and sell shares of its common stock (“Common Stock”) for an aggregate offering price of up to $200,000, through or to Jefferies, acting as sales agent or principal. The shares will be offered and sold under the Company’s shelf registration statement on Form S-3 and a related prospectus declared effective by the Securities and Exchange Commission (the “SEC”) on November 19, 2024. The Company has agreed to pay Jefferies a commission of 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 December 31, 2025, no shares have been issued under the Sales Agreement.

Risks and Uncertainties

The Company is subject to risks and uncertainties common to late-stage clinical biopharmaceutical companies. These risks include, but are not limited to, potential failure of preclinical and clinical studies, uncertainties associated with research and development activities generally, competition from technical innovations of others, dependence upon key personnel, compliance with governmental regulations, the need to obtain marketing approval for any product candidate that the Company may develop, the need to gain broad acceptance among patients, payers and healthcare providers to successfully commercialize any product for which marketing approval is obtained and the need to secure and maintain adequate

intellectual property protection for the Company’s proprietary technology and products. Further, the Company is dependent on third-party service providers for the conduct of its preclinical research, clinical development and manufacturing activities. Product candidates currently under development, including the regimen of bemnifosbuvir and ruzasvir for the treatment of HCV, will require significant amounts of additional capital and additional research and development efforts, and all will require regulatory approval, prior to commercialization. Even if the Company is able to generate revenues from the sale of its product candidates, if any are approved and commercialized, it may not become profitable. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations.

The Company may seek additional capital through one or more of a combination of financing through the sale of additional equity securities, debt financing, or funding in connection with any new collaborative relationships it may enter into or other arrangements. There can be no assurance that the Company will be able to obtain such additional funding, on terms acceptable to the Company, on a timely basis or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s existing stockholders. The Company’s cost of financing and its access to potential sources of future liquidity may be adversely impacted by a number of factors, including, without limitation, then current geopolitical events and the conditions in the financial markets including market volatility and rates of interest and inflation.