6. Equity-Based Compensation

The Company recorded equity-based compensation expense related to all equity-based awards for employees and non-employees, which was allocated as follows in the consolidated statements of operations and comprehensive loss (in thousands):


	Three Months Ended
	March 31,
	2020		2019
Research and development expense	$	815	$	579
General and administrative expense		1,399		1,039
	$	2,214	$	1,618

Restricted Stock

The following table summarizes the Company’s restricted common stock activity as of March 31, 2020:


		Weighted
		Average Fair
		Value per Share
	Number of Shares	at Issuance
Restricted common stock as of December 31, 2019	302,360	$	5.77
Granted	—	$	—
Vested	(75,296)	$	5.77
Forfeited	—	$	—
Restricted common stock as of March 31, 2020	227,064	$	5.77

As of March 31, 2020, the Company had unrecognized equity-based compensation expense of $1.0 million related to restricted stock issued to employees and directors, which is expected to be recognized over a period of 1.1 years.

Stock Options

The following table summarizes the Company’s stock option activity as of March 31, 2020:


				Weighted
		Weighted		Average
	Number of	Average		Remaining	Aggregate
	Shares	Exercise Price		Contractual Term	Intrinsic Value
				(in years)	(in thousands)
Outstanding as of December 31, 2019	2,401,382	$	12.63	8.36	$	6,523
Granted	1,194,385	$	13.66
Exercised	(40,252)	$	10.05
Cancelled	(44,550)	$	14.00
Outstanding as of March 31, 2020	3,510,965	$	12.99	8.76	$	5,298
Options exercisable as of March 31, 2020	887,221	$	11.47	7.57	$	2,620

Using the Black-Scholes option pricing model, the weighted average fair value of options granted during the three months ended March 31, 2020 was $9.64.

The following assumptions were used in determining the fair value of options granted in the three months ended March 31, 2020:


Risk-free interest rate	1.42	%
Expected dividend yield	0.0	%
Expected term (years to liquidity)	6.25
Expected volatility	81.65	%

As of March 31, 2020, the Company has unrecognized equity-based compensation expense related to its employee stock options of $22.9 million which the Company expects to recognize over the remaining weighted average vesting period of 2.9 years.