1.	Description of Business and Basis of Presentation

Avidity Biosciences, Inc. (the Company or Avidity) is a biopharmaceutical company pioneering a new class of oligonucleotide-based therapies called Antibody Oligonucleotide Conjugates (AOCs) designed to overcome the current limitations of oligonucleotide-based therapies in order to treat a wide range of serious diseases. The Company utilizes its proprietary AOC platform to design, engineer and develop therapeutics that combine the tissue selectivity of monoclonal antibodies (mAbs) and the precision of oligonucleotide-based therapies.

The Company was formed under the laws of the State of Delaware in November 2012 as a Delaware limited liability company. In April 2019, pursuant to an Agreement and Plan of Conversion, Avidity Biosciences LLC (Avidity LLC) was converted into Avidity Biosciences, Inc., a Delaware corporation. The entire membership interests of Avidity LLC were converted into securities of Avidity Biosciences, Inc. as follows: (i) each outstanding common unit of Avidity LLC was converted into one share of Avidity Biosciences, Inc.’s common stock; (ii) each outstanding Series A convertible preferred unit of Avidity LLC converted into one share of Avidity Biosciences, Inc.’s Series A convertible preferred stock; and (iii) each outstanding Series B convertible preferred unit of Avidity LLC converted into one share of Avidity Biosciences, Inc.’s Series B convertible preferred stock. All the property, rights, privileges, powers and franchises of Avidity LLC vested in Avidity Biosciences, Inc., and all debts, liabilities and duties of Avidity LLC became debts, liabilities and duties of Avidity Biosciences, Inc. Outstanding convertible notes, warrants and stock awards under Avidity LLC’s employee benefit and incentive compensation plans continued on the same terms and conditions and became binding upon Avidity Biosciences, Inc.

On June 16, 2020, the Company completed its initial public offering (IPO) in which it sold 16,560,000 shares of common stock at an offering price of $18.00 per share. Proceeds from the IPO, net of underwriting discounts, commissions and offering costs, were $274.1 million.

In addition, each of the following occurred in connection with the completion of the IPO:

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the conversion of all outstanding shares of convertible preferred stock into 17,921,069 shares of the Company’s common stock;

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the adjustment of an outstanding warrant to purchase convertible preferred stock into a warrant to purchase 7,809 shares of the Company’s common stock; and

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the amendment and restatement of the Company’s certificate of incorporation, authorizing 400,000,000 shares of common stock and 40,000,000 shares of undesignated preferred stock.

On June 4, 2020, the Company effected a one-for-2.1095 reverse stock split of its common stock (the Reverse Stock Split). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock and the conversion ratio of the convertible preferred stock have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented.

As of December 31, 2020, the Company has devoted substantially all of its resources to organizing and staffing the company, business planning, raising capital, developing its proprietary AOC platform, identifying potential product candidates, establishing its intellectual property portfolio and conducting research and preclinical studies, and providing other general and administrative support for these operations. In addition, the Company has a limited operating history, has incurred operating losses since inception and expects that it will continue to incur net losses into the foreseeable future as it continues the development of its product candidates and development programs. As of December 31, 2020, the Company had an accumulated deficit of $66.5 million and cash, cash equivalents and marketable securities of $328.1 million.

The Company believes that existing cash, cash equivalents and marketable securities, including the net proceeds from the IPO, will be sufficient to fund the Company’s operations for at least 12 months from the date of the filing of this Form 10-K. The Company plans to finance its future cash needs through equity offerings, debt financings or other capital sources, including potential collaborations, licenses and other similar arrangements. If the Company is not able to secure adequate additional funding, it may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or delay or reduce the scope of its planned development programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects.

The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC). The financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The operating results presented in these financial statements are not necessarily indicative of the results that may be expected for any future periods.