Equity Incentive Plans | Note 8. Equity Incentive Plans 2011 Stock Option Plan and 2021 Incentive Award Plan In 2011, the Company established its 2011 Stock Option Plan (the “2011 Plan”), which provided for the granting of stock options to employees and certain nonemployees of the Company. In July 2021, the board of directors and stockholders adopted and approved the 2021 Incentive Award Plan, (the “2021 Plan”). Under the 2021 Plan, the Company has the ability to issue incentive stock options ("ISOs"), nonqualified stock options ("NSOs"), stock appreciation rights, dividend equivalent rights, restricted stock awards, and restricted stock unit awards ("RSUs"). Options under the 2021 Plan can typically be granted for periods of up to ten years. For stock options granted to a grantee who, at the time the option is granted, owned stock representing more than 10% of the voting power of all classes of stock of the Company (or any parent or subsidiary of the Company), the term of the stock option may be granted for periods of up to five years. The ISOs and NSOs will be granted at a price per share not less than the fair value at the date of grant. The exercise price of a stock option granted to a 10% stockholder shall be not less than 110% of the grant date fair value of the shares. Options granted to new hires generally vest over a four-year period, with 25% of the shares vesting on the first anniversary of the grant date and the remaining shares vesting in 36 equal monthly installments thereafter; options granted as merit awards generally vest in 48 equal monthly installments following the grant date. RSUs granted generally vest over a four-year period with straight-line vesting in equal amounts on an annual basis. The Company initially reserved 5,200,000 shares of common stock for future issuance under the 2021 Plan. Pursuant to the evergreen provision in the 2021 Plan, this initial reserve was increased by 2,414,907 and 2,375,235 shares on January 1, 2023 and 2022, respectively. These annual increases under the evergreen provision are equal to the lesser of (i) 5% of the aggregate number of shares of common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of common stock as determined by the Board, subject to certain limitations. The 2011 Plan was superseded by the 2021 Plan at the time of the IPO and no further grants have been made under the 2011 Plan from the date the 2021 Plan became effective. The terms under the 2011 Plan are consistent with those described above for the 2021 Plan. At June 30, 2023 and December 31, 2022 there were 7,297,963 and 6,099,584 shares, respectively, of common stock available for issuance under the 2021 Plan. Stock Option Awards The following table summarizes stock option activity under the 2021 Plan during the periods presented: Number of Weighted-Average Exercise Price Weighted-Average Average Intrinsic Value Balances as of December 31, 2022 4,819,906 $ 9.67 7.7 $ 19,463 Grants 745,800 9.81 Forfeited/cancelled ( 591,416 ) 12.49 Exercised/released ( 104,646 ) 1.52 Balances as of June 30, 2023 4,869,644 $ 9.54 7.4 $ 9,721 Vested and exercisable as of June 30, 2023 2,552,922 $ 7.49 6.4 $ 8,480 Vested and expected to vest as of June 30, 2023 4,869,644 $ 9.54 7.4 $ 9,721 During the three and six months ended June 30, 2023, the Company recorded stock-based compensation expense of $ 2.3 million and $ 4.5 million related to stock option awards, respectively. During the three and six months ended June 30, 2022, the Company recorded stock-based compensation expense of $ 2.6 million and $ 5.1 million related to stock option awards, respectively. The weighted-average grant-date fair values of options granted during the six months ended June 30, 2023 and 2022 was $ 6.94 and $ 9.67 per share, respectively. The aggregate intrinsic value of options exercised was $ 0.5 million and $ 1.0 million during the three and six months ended June 30, 2023, respectively. The aggregate intrinsic value was calculated as the difference between the exercise prices of the underlying options and the estimated fair value of the common stock on the date of exercise. As of June 30, 2023, the unrecognized stock-based compensation expense relating to unvested opti ons was $ 19.4 million, which is expected to be recognized over a weighted-average period of 2.2 years. Determination of Fair Value The Company estimated the grant date fair value of stock options using the Black-Scholes option-pricing model. The fair value of stock options is recognized on a straight-line basis over the requisite service periods of the awards. The fair value of stock options was estimated using the following weighted-average assumptions: Three Months Ended Six Months Ended 2023 2022 2023 2022 Expected term (in years) 6.03 – 6.07 5.98 – 6.04 5.60 – 6.07 5.38 – 6.94 Expected volatility 78.53 % – 79.60 % 58.74 % – 59.24 % 78.53 % – 79.73 % 58.74 % – 60.12 % Risk-free interest rate 3.48 % – 3.65 % 2.82 % – 3.14 % 3.48 % – 3.67 % 1.34 % – 3.14 % Dividend yield – – – – Expected Term The expected term is calculated using the simplified method, which is available if there is insufficient historical data about exercise patterns and post vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant or for each vesting tranche for awards with graded vesting. The midpoint of the vesting date and the maximum contractual expiration date is used as the expected term under this method. For awards with multiple vesting tranches, the time from grant until the midpoints for each of the tranches may be averaged to provide an overall expected term. Expected Volatility The Company used an average historical stock price volatility of a peer group of publicly traded companies to be representative of its expected future stock price volatility, as the Company's trading history for its common stock does not cover the expected term of granted awards. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size, and financial leverage of potential comparable companies. For each grant, the Company measured historical volatility over a period equivalent to the expected term. Risk-Free Interest Rate The risk-free interest rate is based on the implied yield currently available on U.S. Treasury zero-coupon issues with remaining terms equivalent to the expected term of a stock award. Expected Dividend Rate The Company has not paid, and does not anticipate paying, any dividends in the near future. Accordingly, the Company has estimated the dividend yield to be 0 %. Restricted Stock Units RSUs are share awards that entitle the holder to receive freely tradeable shares of the Company’s common stock upon vesting. The RSUs cannot be transferred, and the awards are subject to forfeiture if the holder’s employment terminates prior to the release of the vesting restrictions. The RSUs generally vest over a four-year period with straight-line vesting in equal amounts on an annual basis, provided the employee remains continuously employed with the Company. The fair value of the RSUs is equal to the closing price of the Company’s common stock on the grant date. The following table summarizes restricted share award activity under the 2021 Plan: Number of Weighted-Average Grant Date Fair Value Per Share Outstanding, December 31, 2022 1,014,123 $ 14.25 Grants 1,298,236 9.71 Forfeited/cancelled ( 236,092 ) 12.66 Vested ( 169,832 ) 14.56 Outstanding, June 30, 2023 1,906,435 $ 11.32 During the three and six months ended June 30, 2023, the Company recorded stock-based compensation expense of $ 1.4 million and $ 2.5 million, respectively, related to the RSUs. During the three and six months ended June 30, 2022, the Company recorded stock-based compensation expense of $ 0.8 million and $ 1.3 million, respectively, related to the RSUs. As of June 30, 2023, there was $ 19.1 million of total unrecognized stock-based compensation expense relating to the RSUs that is expected to be recognized over a weighted-average period of 3.2 years. Employee Stock Purchase Plan I n July 2021, the board of directors and stockholders adopted and approved the 2021 Employee Stock Purchase Plan (the “ESPP”). The Company initially reserved 850,000 shares of common stock for future issuance under the ESPP. Pursuant to the evergreen provision under the ESPP, t his initial reserve was increased by 482,981 and 475,047 shares on January 1, 2023 and 2022, respectively. These annual increases were effected pursuant to an evergreen provision in the ESPP, and are equal to the lesser of (i) 1% of the aggregate number of shares of common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of common stock as determined by the board of directors, subject to certain limitations. The Company has two offering periods annually, running for six-months, with the first offering period beginning in the second quarter, and the second offering period beginning in the fourth quarter. The purchase of shares for participants in the ESPP occurs at the conclusion of each offering period. For the six months ended June 30, 2023, participants in the ESPP purchased 78,534 shares for a total of $ 0.7 million. As of June 30, 2023, the Company has collected payroll withholdings of $ 0.2 million in the current offering period for the purchase of shares under the ESPP. The Company recorded stock-based compensation expense associated with the ESPP of $ 0.1 million and $ 0.3 million for the three and six months ended June 30, 2023, respectively. The Company recorded stock-based compensation expense associated with the ESPP of $ 0.1 million for both the three and six months ended June 30, 2022. As of June 30, 2023, there were 1,630,570 shares of common stock available for issuance under the ESPP. The fair value of shares to be issued under the Company's 2021 ESPP was estimated using the Black-Scholes valuation model with the following assumptions for the three and six months ended June 30, 2023: Three Months Ended Six Months Ended 2023 2022 2023 2022 Expected term (in years) 0.48 – 0.50 0.50 0.48 – 0.50 0.50 Expected volatility 66.72 % – 97.38 % 76.50 % 66.72 % – 97.38 % 76.50 % Risk-free interest rate 4.62 % – 5.32 % 1.51 % 4.62 % – 5.32 % 1.51 % Dividend yield – – – – Stock-Based Compensation The following is a summary of stock-based compensation expense by function (in thousands): Three Months Ended Six Months Ended 2023 2022 2023 2022 Cost of goods sold $ 71 $ 42 $ 130 $ 78 Research and development 587 410 1,115 753 Selling, general and administrative 3,084 3,080 6,020 5,675 Total stock-based compensation expense $ 3,742 $ 3,532 $ 7,265 $ 6,506 |