|3 Months Ended|
Mar. 31, 2021
|Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]|
8. Stock-Based Compensation
Stock Incentive Plans
2018 Equity Incentive Plan
In June 2018, the Company’s board of directors adopted and its stockholders approved the 2018 Equity Incentive Plan (the “2018 Plan”), which became effective as of June 20, 2018, at which point no further grants could be made under the 2015 Equity Incentive Plan (the “2015 Plan”) described below. Under the 2018 Plan, the Company may grant incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. As of March 31, 2021, options to purchase 5,350,986 shares of common stock were outstanding and 929,904 shares were available for future issuance under the 2018 Plan.
Initially, subject to adjustment as provided in the 2018 Plan, the aggregate number of shares of the Company’s common stock authorized for issuance pursuant to stock awards under the 2018 Plan was 4,000,000 shares, which is the sum of (i) 1,600,692 shares plus (ii) the number of shares reserved and available for issuance under the 2015 Plan at the time the 2018 Plan became effective and (iii) the number of shares subject to stock options or other stock awards granted under the 2015 Plan that expire, terminate are forfeited or otherwise not issued, or are withheld to satisfy a tax withholding obligation in connection with an award or to satisfy a purchase or exercise price of an award (such as upon the expiration or termination of a stock award prior to vesting). The number of shares of the Company’s common stock reserved for issuance under the 2018 Plan automatically increases on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2028, by 5% of the total number of shares of capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Company’s board of directors prior to such increase. The maximum number of shares that may be issued upon the exercise of ISOs under the 2018 Plan is 12,500,000 shares.
2015 Equity Incentive Plan
The Company’s 2015 Plan provided for the granting of ISOs and NSOs to employees, directors and consultants at the discretion of its board of directors. The 2015 Plan was terminated as to future awards in June 2018, although it continues to govern the terms of options that remain outstanding under the 2015 Plan.
No additional stock awards will be granted under the 2015 Plan, and all outstanding stock awards granted under the 2015 Plan that are repurchased, forfeited, expire or are cancelled will become available for grant under the 2018 Plan in accordance with its terms.
Options granted under the 2015 Plan expire no later than 10 years from the date of grant. Options granted under the 2015 Plan vest over periods determined by the Company’s board of directors, generally over four years. The 2015 Plan allows for early exercise of certain options prior to vesting. Upon termination of employment, the unvested shares are subject to repurchase at the original exercise price. As of March 31, 2021, options to purchase 1,798,854 shares of common stock were outstanding under the 2015 Plan.
2018 Employee Stock Purchase Plan
In June 2018, the Company’s board of directors adopted and its stockholders approved the 2018 Employee Stock Purchase Plan (the “ESPP”), which became effective as of June 20, 2018. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the U.S. Internal Revenue Code of 1986, as amended. The number of shares of common stock initially reserved for issuance under the ESPP was 200,000 shares. The ESPP provides for an annual increase on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2028, equal to the lesser of (i) 1% of the shares of common stock outstanding on the last day of the prior fiscal year or (ii) 375,000 shares, or a lesser number of shares determined by the Company’s board of directors prior to such increase. As of March 31, 2021, 137,668 shares of common stock had been issued under the ESPP and 820,556 shares remained available for future issuance under the ESPP. The price per share of common stock to be paid by an ESPP participant on the applicable purchase date of an offering period shall be equal to 85% of the lesser of the fair market value of a share of common stock on (i) the applicable offering date or (ii) the applicable purchase date. The Company’s board of directors authorized an initial six-month offering period beginning on November 16, 2018 and ending on May 15, 2019. The Company’s board of directors has subsequently authorized additional six-month offering periods, with the most recent offering period beginning on November 16, 2020.
Stock Option Activity
The following table summarizes activity under the Company’s stock option plans and related information (in thousands, except share and per share amounts):
The weighted average grant date fair value of options granted during the three months ended March 31, 2021 was $3.95 per share. The aggregate intrinsic value of exercised stock options during the three months ended March 31, 2021 was $41,000. The aggregate intrinsic value is calculated as the difference between the exercise price and the estimated fair value of the Company’s common stock at the date of exercise.
Stock-Based Compensation Expense
Total stock-based compensation expense recognized by function was as follows (in thousands):
As of March 31, 2021, the unrecognized stock-based compensation cost was $18.4 million with an estimated weighted average amortization period of 3.1 years.
The fair value of the stock options granted is calculated using the Black-Scholes option-pricing model with the following range of assumptions:
The expected term of options granted represents the period of time that options granted are expected to be outstanding and was determined by calculating the midpoint between the date of vesting and the contractual life of each option. The expected term of the ESPP rights is equal to the look-back period. Volatility is based on the average historical volatility of a peer group of public companies over the expected term. The peer group was selected on the basis of operational and economic similarity with the Company’s principal business operations. The risk-free interest rate for the expected term of the options is based on the U.S. Treasury yield curve with a maturity equal to the expected term in effect at the time of grant. The Company has not paid, and does not anticipate paying, cash dividends on its shares of common stock; therefore, the expected dividend yield is zero.
The entire disclosure for share-based payment arrangement.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef