13. STOCK BASED AWARDS

In April 2014, the Company adopted the Corbus Pharmaceuticals Holdings, Inc. 2014 Equity Incentive Plan (the “2014 Plan”). Pursuant to the 2014 Plan, the Company’s Board of Directors (the "Board") may grant incentive and nonqualified stock options and restricted stock to employees, officers, directors, consultants and advisors.

Pursuant to the terms of an annual evergreen provision in the 2014 Plan, the number of shares of common stock available for issuance under the 2014 Plan shall automatically increase on January 1 of each year by at least seven percent (7%) of the total number of shares of common stock outstanding on December 31st of the preceding calendar year, or, pursuant to the terms of the 2014 Plan, in any year, the Board may determine that such increase will provide for a lesser number of shares.

In accordance with the terms of the 2014 Plan, and pursuant to the annual evergreen provision contained in the 2014 plan, effective as of January 1, 2021, the number of shares of common stock available for issuance under the 2014 Plan increased by 2,500,000 shares, which was less than seven percent (7%) of the outstanding shares of common stock on December 31, 2020. As of January 1, 2021, there was a total of 25,570,842 shares reserved for issuance under the 2014 plan and there were 9,869,051 shares available for future grants. As of March 31, 2021 there were 4,941,899 shares available for future grants.

In accordance with the terms of the 2014 Plan, and pursuant to the annual evergreen provision contained in the 2014 Plan, effective as of January 1, 2022, the number of shares of common stock available for issuance under the 2014 Plan increased by 8,766,162 shares, which was seven percent (7%) of the outstanding shares of common stock on December 31, 2021. As of January 1, 2022, the 2014 Plan had a total reserve of 34,337,004 shares and there were 16,760,151 shares available for future grants. As of March 31, 2022 there were 12,794,566 shares available for future grants.

Share-based Compensation

For stock options issued and outstanding and restricted stock awards for the three months ended March 31, 2022 and 2021, respectively, the Company recorded non-cash, stock-based compensation expense of $1,591,746 and $2,580,402, net of estimated forfeitures.

The fair value of each option award is estimated on the date of grant using the Black-Scholes option pricing model that uses the assumptions noted in the following table. The Company uses historical data, as well as subsequent events occurring prior to the issuance of the financial statements, to estimate option exercises and employee terminations in order to estimate its forfeiture rate. The expected term of options granted under the 2014 Plan, all of which qualify as “plain vanilla” per SEC Staff Accounting Bulletin 107, is determined based on the simplified method due to the Company’s limited operating history, and is 6.25 years based on the average between the vesting period and the contractual life of the option. For non-employee options, the expected term is the contractual term. The risk-free rate is based on the yield of a U.S. Treasury security with a term consistent with the option.

The weighted average grant-date fair value of options granted during the three months ended March 31, 2022 and 2021 was $0.37 and $2.09 per share, respectively. The aggregate intrinsic value of options exercised during the three months ended March 31, 2022 and 2021 was approximately $0 and $1,735,214, respectively. The total fair value of options that were vested as of March 31, 2022 and 2021 was $34,527,881 and $36,311,140, respectively. As of March 31, 2022, there was approximately $10,437,667 of total unrecognized compensation expense, related to non-vested share-based option compensation arrangements. The unrecognized compensation expense is estimated to be recognized over a period of 2.49 years as of March 31, 2022.

During the three months ended March 31, 2022, the Company granted 25,000 restricted stock awards under the 2014 Plan. As of March 31, 2022, the 25,000 restricted stock awards were fully vested. No restricted stock awards were granted in the three months ended March 31, 2021.