NATURE OF BUSINESS AND BASIS OF PRESENTATION Keros Therapeutics, Inc. (Keros or the Company) was incorporated in 2015 as a Delaware corporation. Its principal offices are in Lexington, Massachusetts. The Company is a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of novel treatments for patients suffering from hematological and musculoskeletal disorders with high unmet medical need. The accompanying unaudited interim condensed consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP) and include the accounts of the Company and its wholly owned Australian subsidiary, Keros Therapeutics Australia Pty Ltd (Keros Australia). All significant intercompany transactions and accounts have been eliminated in consolidation. Since its inception in 2015, the Company has devoted the majority of its resources on business planning, research and development of its product candidates, including by conducting clinical trials and preclinical studies, raising capital and recruiting management and technical staff to support these operations. To date, the Company has not generated any revenue from product sales as none of its product candidates have been approved for commercialization. As of March 31, 2020, the Company has funded its operations primarily with proceeds from the sale of convertible preferred stock (see Note 6) and its research collaboration and exclusive license agreement with Novo Nordisk A/S. On April 13, 2020, the Company completed an initial public offering (IPO) in which the Company issued and sold 6,900,000 shares of its common stock, which includes 900,000 shares issued and sold pursuant to the full exercise of the underwriters option to purchase additional shares, at a public offering price of $16.00 per share, for aggregate gross proceeds of $110.4 million. The Company received approximately $99.8 million in net proceeds after deducting underwriting discounts and commissions and offering costs. In connection with the IPO, the Company's board of directors (the "Board") and stockholders approved an amended and restated certificate of incorporation to, among other things, effect a one-for-2.1703 reverse stock split of its issued and outstanding shares of common stock and convertible preferred stock, as well as to effect a proportional adjustment to the existing conversion ratios for the Companys convertible preferred stock. The reverse stock split was effected on March 31, 2020. Accordingly, all share and per share amounts of common stock for all periods presented in the accompanying unaudited interim condensed consolidated financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect this reverse stock split and adjustment of preferred stock conversion ratios. Upon the closing of the IPO, all of the then-outstanding shares of convertible preferred stock automatically converted into 10,725,129 shares of common stock at the applicable conversion ratio then in effect. Subsequent to the closing of the IPO, there were no shares of convertible preferred stock outstanding. The unaudited interim condensed consolidated financial statements as of March 31, 2020, including share and per share amounts, do not give effect to the IPO, as it closed subsequent to March 31, 2020. The Companys condensed consolidated financial statements have been prepared on the basis of the Company continuing as a going concern for the next 12 months. Management believes that the Companys existing cash and cash equivalents, together with the net proceeds from the IPO, will allow the Company to continue its operations for at least the next 12 months. In the absence of a significant source of recurring revenue, the continued viability of the Company beyond that point is dependent on its ability to continue to raise additional capital to finance its operations. If the Company is unable to obtain additional funding, the Company may be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. The accompanying unaudited interim condensed consolidated financial statements as of March 31, 2020 and for the three months ended March 31, 2020 and 2019 have been prepared by the Company in conformity with generally accepted accounting principles in the United States of America (U.S. GAAP) and, pursuant to the rules and regulations of Article 10 of Regulation S-X of the Securities Act published by the Securities and Exchange Commission (SEC) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes the disclosures are adequate. These unaudited interim condensed consolidated financial statements should be read in conjunction with the Companys audited financial statements and notes thereto for the year ended December 31, 2019 included in the Companys final prospectus that forms part of the Companys Registration Statement on Form S-1 (Reg. No. 333-237212), filed with the SEC pursuant to Rule 424(b)(4) on April 8, 2020 (the Prospectus). The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of management, the accompanying unaudited interim condensed consolidated financial statements contain all adjustments which are necessary for a fair presentation of the Companys condensed consolidated balance sheets as of March 31, 2020 and December 31, 2019, condensed consolidated statements of operations for the three months ended March 31, 2020 and 2019 and condensed consolidated cash flows for the three months ended March 31, 2020 and 2019. Such adjustments are of a normal and recurring nature. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2020.