10. Stockholders’ equity

Issuance of Securities through an Underwritten Public Offering

On January 22, 2021, the Company issued and sold an aggregate of 5,400,000 shares of its common stock in an underwritten public offering at a public offering price of $14.00 per share, resulting in gross proceeds of $75.6 million before deducting underwriting discounts and commissions and other transaction expenses of approximately $5.1 million. The public offering was made pursuant to an underwriting agreement entered into by the Company with Cowen and Company, LLC and Piper Sandler & Co., as representatives of the several underwriters, on January 19, 2021. The shares were issued pursuant to a shelf registration statement on Form S-3 that was filed with the SEC on June 12, 2020 and declared effective by the SEC on June 22, 2020.

Issuance of Securities through a Private Placement

On December 8, 2020, the Company issued in a private placement 10,312,500 shares of common stock, and, in lieu of shares of common stock, pre-funded warrants (the “Pre-Funded Warrants”) to purchase an aggregate of 1,000,000 shares of common stock, and, in each case, accompanying Warrants to purchase an aggregate of up to 2,828,125 additional shares of common stock (or Pre-Funded Warrants to purchase common stock in lieu thereof) at a price of $8.00 per share and accompanying Warrant (or $7.99 per Pre-Funded Warrant and accompanying Warrant). The private placement resulted in aggregate gross proceeds of $90.5 million, before $0.4 million of transaction costs.

In the event of certain fundamental transactions involving the Company, the holders of Warrants may require the Company to make a payment based on a Black-Scholes valuation, using specified inputs. The holders of Pre-Funded Warrants do not have similar rights. Therefore, the Company accounted for the Warrants as liabilities, while the Pre-Funded Warrants met the permanent equity criteria classification. The Pre-Funded Warrants are classified as a component of permanent equity because they are freestanding financial instruments that are legally detachable and separately exercisable from the shares of common stock with which they were issued, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, and permit the holders to receive a fixed number of shares of common stock upon exercise. In addition, the Pre-Funded Warrants do not provide any guarantee of value or return. The initial fair value of the Warrants at issuance was $19.3 million, determined using the Black-Scholes valuation model. The Company remeasured the Warrants’ fair value at September 30, 2021 and December 31, 2020 as $5.6 million and $19.7 million, respectively. The change in fair value of $1.8 million and $14.1 million was recorded in the condensed statement of operations for the three and nine months ended September 30, 2021, respectively.

Convertible Preferred Stock and 2019 Warrants

On April 9, 2019, the Company completed two concurrent underwritten public offerings of its equity securities. In the first public offering, the Company sold 8,667,333 shares of its common stock and accompanying Class A warrants (the “2019 Warrants”) to purchase 1,951,844 shares of the Company’s common stock at a combined price to the public of $7.50 per common share and accompanying 2019 Warrant. In the second public offering, the Company sold 666 shares of its Series A convertible preferred stock (the “Series A Preferred Stock”) and accompanying 2019 Warrants to purchase 166,500 shares of the Company’s common stock at a combined public offering price of $7,500 per share and accompanying 2019 Warrant. The offerings resulted in aggregate gross proceeds to the Company of $70.0 million, before underwriting discounts and commissions and offering expenses payable by the Company of approximately $5.0 million.

In November 2019, all 666 shares of Series A Preferred Stock were converted by the holder into 666,000 shares of common stock. As of September 30, 2021, there were no shares of Series A Preferred Stock outstanding.

Each 2019 Warrant has an exercise price per share of common stock of $8.625, subject to adjustment in certain circumstances, and will expire on October 10, 2022. Each 2019 Warrant is immediately exercisable, provided that the holder is prohibited, subject to certain exceptions, from exercising the 2019 Warrant for shares of the Company’s common stock to the extent that immediately prior to or after giving effect to such exercise, the holder, together with its affiliates and other attribution parties, would own more than 4.99% of the total number of shares of the Company’s common stock then issued and outstanding. This percentage may be changed at the holders’ election to a higher or lower percentage upon 61 days’ notice to the Company.

The Company evaluated the Series A Preferred Stock and 2019 Warrants for liability or equity classification in accordance with the provisions of ASC 480, Distinguishing Liabilities from Equity, and determined that equity treatment was appropriate because neither the Series A Preferred Stock nor the 2019 Warrants met the definition of liability instruments.

The 2019 Warrants are classified as a component of permanent equity because they are freestanding financial instruments that are legally detachable and separately exercisable from the shares of common stock with which they were issued, are immediately exercisable, do not embody an obligation for the Company to repurchase its shares, and permit the holders to receive a fixed number of shares of common stock upon exercise. In addition, the 2019 Warrants do not provide any guarantee of value or return. The Company valued the 2019 Warrants at issuance using the Black-Scholes option pricing model and determined the fair value of the 2019 Warrants to purchase 2,118,344 shares of the Company’s common stock was $9.0 million. The key inputs to the valuation model included an average volatility of 86.06% and an expected term of 3.5 years.

As of September 30, 2021, 2019 Warrants to purchase 2,117,094 shares of common stock are outstanding and remain unexercised.