Common stock

In November 2020, we entered into an at-the-market offering program (the “2020 ATM Program”) relating to shares of our common stock. The 2020 ATM Program permitted us to offer and sell shares of our common stock having an aggregate offering price of up to

$50.0

million from time to time through or to the sales agent under the 2020 ATM Program. Sales of our common stock were permitted to be made from time to time in at-the-market offerings as defined in Rule 415 of the Securities Act of 1933, as amended (the “Securities Act”), including by means of ordinary broker’s transactions on the Nasdaq Stock Exchange or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices, or as otherwise agreed to with the sales agent. The sales agent was entitled to compensation at a fixed commission rate of

3.0%

of the aggregate gross sales price per share sold. As of February 8, 2021, sales of shares of our common stock under the 2020 ATM Program were completed when we sold an aggregate total of

28.6

million shares of our common stock at an average sale price of

$1.75

per share, and we received net proceeds of

$47.3

million, after deducting the underwriting discounts and commissions and estimated offering expenses.

In February 2021, we closed on an underwritten public offering of our common stock, pursuant to which we issued an aggregate total of

59.5

million shares of our common stock at an offering price of

$1.85 per share, and we received net proceeds of $96.6

million, after deducting the underwriting discounts and commissions and estimated offering expenses.

In March 2021, we entered into an at-the-market offering program (the “2021 ATM Program”) relating to shares of our common stock. The 2021 ATM Program permits us to offer and sell shares of our common stock having an aggregate offering price of up to

$100.0

million from time to time through or to the under the 2021 ATM Program sales agent. Sales of our common stock may be made from time to time in at-the-market offerings as defined in Rule 415 of the Securities Act, including by means of ordinary broker’s transactions on the Nasdaq Stock Exchange or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices, or as otherwise agreed to with the sales agent. The investment bank will be entitled to compensation at a fixed commission rate of

3.0%

of the aggregate gross sales price per share sold. The sales agent is not required to sell any specific number or dollar amounts of securities but will act as sales agent and use commercially reasonable efforts to sell on our behalf all of the shares of common stock requested to be sold by us, consistent with its normal trading and sales practices, on mutually agreed terms between us and the sales agent. Through March 31, 2021, we have sold

4.8

million shares of our common stock at an average sale price of

$1.59

per share and we received estimated net proceeds of

$7.0

million, after deducting the underwriting discounts and commissions and estimated offering expenses. Subsequently, and through the date of this 10-Q Report filing, we have not sold any additional shares of our common stock under the 2021 ATM Program. Future sales, if any, under the 2021 ATM Program will depend on a variety of factors, including among others, market conditions, the trading price of our common stock, determinations by us of the appropriate sources of funding, and potential uses of funding available to us.

Restricted stock units

During the three months ended March 31, 2021, we granted 327 thousand restricted stock units (“RSUs”) at a weighted average grant date fair value of $1.58 per unit. The weighted average vesting life of these RSUs was 2.1 years. Additionally, we settled 52 thousand vested RSUs during the three months ended March 31, 2021 and the weighted average grant date fair value of these RSUs was $1.86 per unit. Furthermore, during the three months ended March 31, 2021, there were 732

thousand RSUs that vested, but were not yet settled as of March 31, 2021, and for which the weighted average grant date fair value was $1.07 per unit. We anticipate that settlement of these RSUs will occur in May 2021.

Warrants

In March 2021, a warrant holder exercised the holder’s right to purchase an aggregate of

205 thousand shares of our common stock for $50 thousand. Also, in March 2021, warrant holders exercised their rights to purchase an aggregate of 358 thousand shares of common stock pursuant to the warrant’s cashless exercise provision, wherein 298

thousand shares of our common stock were issued. In total, during the three months ended March 31, 2021, warrants to purchase an aggregate of

563 thousand shares of common stock were exercised and the weighted average exercise price of these warrants was $0.24 per share.