As of September 30, 2021, there were 119,787,380 shares of our common stock outstanding.

In August 2019, we sold 18,525,000 shares of our common stock, par value $0.001 per share, 4,840 shares of our Series B Convertible Preferred Stock, par value $0.001 per share (“Series B Preferred Stock”) and warrants to purchase up to an aggregate of

5,841,250 shares of our common stock in an underwritten public offering (the “Offering”) for aggregate net proceeds of approximately $65.6 million.

Investment funds associated with Bain Capital Life Sciences Investors, LLC (“Bain Capital Life Sciences”) purchased approximately $35.0 million of common stock, Series B Preferred Stock and warrants in the Offering on the same terms as the other investors in the Offering. Following the Offering, Andrew A. F. Hack, M.D., Ph.D., a Managing Director of Bain Capital Life Sciences, was appointed to our board of directors.

In June 2021, Bain Capital Life Sciences and its affiliates sold warrants to purchase an aggregate of 2,916,250 shares of our common stock for aggregate consideration of $11.8 million, representing all of the warrants held by Bain Capital Life Sciences and its affiliates.

In May 2020, we completed an underwritten public offering of 16,100,000 shares of our common stock, par value $0.001 per share, including 2,100,000 shares sold pursuant to the full exercise of an overallotment option previously granted to the underwriters. All of the shares were offered at a price to the public of $5.00 per share. The net proceeds to us from this offering were approximately $75.4 million, after deducting the underwriting discount and other estimated offering expenses payable by us. Bain Life Sciences Funds purchased 1,000,000 shares of common stock in the underwritten public offering. Bain Capital Life Sciences is the general partner of Bain Life Sciences Funds. The participation by Bain Life Sciences Funds was on the same terms as the other investors in the offering.

On August 6, 2020, we entered into an at-the-market Sales Agreement (the “2020 ATM Agreement”) with Cowen and Company, LLC (“Cowen”), under which we may offer and sell from time to time, at our sole discretion, shares of our common stock having an aggregate offering price of up to $150 million through Cowen as our sales agent. We agreed to pay Cowen a commission of up to 3% of the gross sales proceeds of any common stock sold through Cowen under the 2020 ATM Agreement. For the nine months ended September 30, 2021, we received net cash proceeds of $28.2 million resulting from sales of 2,878,567 shares of our common stock pursuant to the 2020 ATM Agreement. All of these shares were sold during the three months ended March 31, 2021. As of September 30, 2021, we had $120.5 million remaining under the 2020 ATM Agreement.

In August 2021, all of the 4,140 shares of Series B Preferred Stock were converted into 4,140,000 shares of common stock. As of September 30, 2021, there were no shares of Series B Preferred Stock outstanding.

During the nine months ended September 30, 2021, 946,150 of our common stock warrants were exercised. As of September 30, 2021, the following common stock warrants were outstanding:

Warrants Issuance Date

Shares Issuable
(in thousands)

Expiration Date

Exercise Price
per Share

Outstanding as of
September 30, 2021
(in thousands)

August 12, 2019

4,895

February 12, 2022

4.50

4,895

Warrants were exercisable upon issuance. The holder is prohibited from exercising these warrants if, as a result of such exercise, the holder and its affiliates, would own more than 4.99% of the total number of shares of common stock then issued and outstanding, which percentage may be changed at the holders’ election to a higher or lower percentage (not to exceed 19.99%) upon 61 days’ notice to the Company.

The warrants contain provisions that may obligate us to repurchase them for an amount that does not represent fair value in the event of a change of control. Due to this provision, the warrants do not meet the criteria to be considered indexed to our own stock. Accordingly, we recorded the warrants as a derivative liability.

The warrants will be revalued at each reporting period using the Black-Scholes model and the change in the fair value of the warrants will be recognized as other income (expense) in the condensed consolidated statements of operations. At September 30, 2021, the estimated fair value of warrant liability was $72.0 million. For the three and nine months ended September 30, 2021, we recognized the increase in the estimated fair value of warrant liability of $45.1 million and $68.6 million, respectively, as expense in other income (expense) in our condensed consolidated statements of operations. For the three and nine months ended September 30, 2020, we recognized the decrease in the estimated fair value of warrant liability of $21.2 million and $4.2 million, respectively, as income in other income (expense) in our condensed consolidated statements of operations.