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 may grant incentive and nonqualified stock options and restricted stock to employees, officers, directors, consultants and advisors. On January 1, 2016, pursuant to an annual evergreen provision contained in the 2014 Plan, the number of shares reserved for future grants was increased by 1,250,000 shares, respectively. As of December 31, 2016, there was a total of 9,916,017 shares reserved for issuance under the 2014 Plan and there were 2,840,133 shares available for future grants. Options issued under the 2014 Plan are exercisable for up to 10 years from the date of issuance.

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 of Directors may determine that such increase will provide for a lesser number of shares. In accordance with the terms of the 2014 Plan, effective as of January 1, 2017, the number of shares of common stock available for issuance under the 2014 Plan increased by 3,127,722 shares, which was seven percent (7%) of the outstanding shares of common stock on December 31, 2016. As of January 1, 2017, the 2014 Plan had a total reserve of 13,043,739 shares and there were 5,967,855 shares available for future grants.

Share-based Compensation

For stock options issued and outstanding for the years ended December 31, 2016 and 2015, the Company recorded non-cash, stock-based compensation expense of $3,163,534 and $1,153,302, respectively, 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. Due to its limited operating history and limited number of sales of its common stock, the Company estimated its volatility in consideration of a number of factors, including the volatility of comparable public companies and, commencing in 2015, the Company also included the volatility of its own common stock. 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 within the valuation model. The expected term of options granted under the 2014 Plan, all of which qualify as “plain vanilla” per SEC Staff Accounting Bulletin 107, is based on the average of the 6.25 years. 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 assumptions used principally in determining the fair value of options granted were as follows:

A summary of option activity for years ended December 31, 2016 and 2015 is presented below:

The weighted average grant-date fair value of options granted during the years ended December 31, 2016 and 2015 was $3.81 and $1.41 per share, respectively. The aggregate intrinsic value of options exercised during the years ended December 31, 2016 and 2015 was approximately $1,004,321 and $152,531, respectively. The total fair value of options that were vested as of December 31, 2016 was $2,561,877. As of December 31, 2016 there was approximately $9,232,486 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 3.03 years at December 31, 2016.