Stockholders' Equity | . Stockholders’ Equity 2020 Equity Incentive Plan The Company may grant awards of common stock under the 2020 Equity Incentive Plan (the "2020 Plan") to the Company’s employees, consultants and non-employee directors pursuant to option awards, stock appreciation rights awards, restricted stock awards, restricted stock unit awards, performance stock awards, performance stock unit awards and other stock-based awards. As of March 31, 2022 and December 31, 2021 , the total number of common shares authorized for issuance under the 2020 Plan was 7,658,509 and 6,226,540 , respective ly. On January 1st of each year, commencing with the first January 1st following the effective date of the 2020 Plan, the shares authorized for issuance under the 2020 Plan shall be increased by a number of shares equal to the lesser of 4% of the total number of shares outstanding on the immediately preceding December 31st and such lesser number of shares determined by the Company’s board of directors. The maximum term of the options granted under the 2020 Plan is no more than ten years. Awards under the 2020 Plan generally vest at 25 % one year from the vesting commencement date and ratably each month thereafter for a period of 36 months , subject to continuous service. Stock-based compensation expense for the three months ended March 31, 2022 and 2021 has been reported in the condensed consolidated statements of operations and comprehensive loss as follows (in thousands): Three Months Ended 2022 2021 Research and development $ 1,300 $ 954 General and administrative 2,332 3,689 Total $ 3,632 $ 4,643 Restricted Stock Units The following table summarizes RSU activity under the 2020 Plan for the three months ended March 31, 2022: Number of Weighted - Average Outstanding at December 31, 2021 975,046 $ 18.00 Granted — $ — Vested ( 112,473 ) $ 18.00 Outstanding at March 31, 2022 862,573 $ 18.00 As of March 31, 2022, total unrecognized stock-based compensation expense for RSUs was $ 15.5 million, which is expected to be recognized over a remaining weighted-average period of approximately 2.0 years . During the three months ended March 31, 2021, the Company modified 138,461 RSU's under the Transition Agreement (See Note 9). Stock Options The following table summarizes stock option activity under the 2020 Plan for the three months ended March 31, 2022: Number of Weighted - Average Weighted -Average Aggregate Balance at December 31, 2021 1,086,902 $ 26.76 9.22 $ 991,495 Granted 1,391,000 $ 6.68 Exercised — $ — Balance at March 31, 2022 2,477,902 $ 15.49 9.49 $ 3,000 Vested and expected to vest at March 31, 2022 2,477,902 $ 15.49 9.49 $ 3,000 Exercisable at March 31, 2022 209,947 $ 25.46 8.81 $ — As of March 31, 2022 , total unrecognized stock-based compensation cost for unvested common stock options was $ 19.6 million, which is expected to be recognized over a remaining weighted-average period of approximately 3.5 years. The weighted- average grant date fair value of stock options granted during the three months ended March 31, 2022 was $ 4.42 per share . The total fair value of options vested during the three months ended March 31, 2022 was $ 0.9 million. During the three months ended March 31, 2021 the Company modified 7,747 stock options under the Transition Agreement (See Note 9). The assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Three Months Ended 2022 2021 Expected volatility 74.6 % 76.4 % Risk-free interest rate 1.88 % 0.52 % Expected dividend yield 0.0 % 0.0 % Expected term 4.42 years 4.77 years Expected volatility. As the Company’s common stock does not have a significant trading history, the expected volatility assumption is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology industry. Risk-free interest rate. The Company bases the risk-free interest rate assumption on the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. Expected dividend yield. The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present plans to pay cash dividends. Expected term. For employees, the expected term represents the period of time that options are expected to be outstanding. Because the Company has minimal historical exercise behavior, it determines the expected life assumption using the simplified method, which is an average of the contractual term of the option and its vesting period. For nonemployees, the expected term is generally the contractual term of the option. Employee Stock Purchase Plan The BioAtla, Inc. Employee Stock Purchase Plan (the “ESPP”) permits participants to purchase common stock through payroll deductions of up to 15 % of their eligible compensation. As of March 31, 2022 and December 31, 2021, a total of 1,229,148 shares and 833,993 shares, respectively, of common stock were authorized for issuance under the ESPP. The number of shares of common stock authorized for issuance will automatically increase on January 1 of each calendar year, from January 1, 2021 through January 1, 2030 by the least of (i) 1.0 % of the total number of common shares of our common stock outstanding on December 31 of the preceding calendar year (calculated on a fully diluted basis), (ii) 929,658 common shares or (iii) a number determined by the Company’s board of directors that is less than (i) and (ii). In February 2021, employees began to enroll in the ESPP and the Company’s first offering period commenced. The Company did not issue any shares under the ESPP during the three months ended March 31, 2022 or March 31, 2021. As of March 31, 2022 , 1,217,966 shares of common stock remained available for issuance under the ESPP. Stock-based compensation expense related to the ESPP for the three months ended March 31, 2022 and 2021 was immaterial. Common Stock Warrants The Company issued warrants in 2016 in connection with certain advisory services. The warrants became exercisable upon our IPO for a period of 365 and 450 days. Upon adoption of ASU No. 2018-07 on October 1, 2020, the measurement date of the warrants became fixed in accordance with the guidance, and such fair value was nominal since the warrants were deeply out-of-the-money. In December 2021, a total of 566,586 warrants with an exercise period of 365 days after our IPO expired unexercised. The remaining 151,088 warrants with an exercise period of 450 days after the Company's IPO expired unexercised in March 2022. Accordingly, there were no remaining common stock warrants outstanding and exercisable as of March 31, 2022. Common Stock Reserved for Future Issuance Common stock reserved for future issuance are as follows in common equivalent shares: March 31, December 31, Warrants for the purchase of common stock — 151,088 Common stock options and restricted stock units issued and outstanding 3,340,475 2,061,948 Awards available for future issuance under the 2020 Plan 3,252,823 3,211,854 Awards available for future issuance under the ESPP 1,217,966 822,811 Total common stock reserved for future issuance 7,811,264 6,247,701 |