The Company maintains two equity compensation plans: the 2017 Stock Incentive Plan (the “2017 Plan”) and the 2019 Inducement Equity Incentive Plan (the “2019 Inducement Plan”). In June 2020, the board of directors approved an increase of 700,000 shares of common stock for issuance under the 2019 Inducement Plan.

During 2019, the Company granted 100,000 options and 50,000 restricted stock units (“RSUs”) containing the same performance-based vesting criteria. These options and RSUs (the “Performance Awards”) are subject to performance-based vesting eligibility and a subsequent partial time-based vesting schedule. Specifically, the Performance Awards are eligible for vesting based on the achievement of performance criteria, each representing a 25% vesting opportunity if achieved within a specified time during the performance period (the “Performance Period”), and relating to (i) the release of tebipenem HBr top-line data; (ii) FDA acceptance of a tebipenem HBr New Drug Application; (iii) non-dilutive financing; and (iv) equity financing. Following the Performance Period, Performance Awards determined to be eligible for vesting as a result of achievement of the performance criteria will vest as follows: (a) 50% of the eligible award will vest immediately, and (b) the remaining eligible award will vest (i) in the case of options, in equal monthly installments ending two years after the Performance Period expiration, and (ii) in the case of RSUs, on such two year anniversary.

In January 2021, the Company cancelled the performance-based awards due to the non-achievement of the performance-based vesting criteria, and the awards were added back to the shares of common stock available for issuance under the 2017 Plan. None of the outstanding options had vested and no compensation expense associated with performance-based awards was recognized as of March 31, 2021.

The following table summarizes the activity of options and RSUs under the 2017 Plan containing performance-based vesting criteria during the three months ended March 31, 2021:

	Number of Performance Based Option Shares			Number of Performance Based RSU Shares
Outstanding as of December 31, 2020		63,107			30,561
Granted		-			-
Exercised		-			-
Forfeited or cancelled		(63,107	)		(30,561	)
Outstanding as of March 31, 2021		-			-

The weighted-average grant date fair value of options, estimated as of the grant date using the Black-Scholes option pricing model, was $14.57 and $6.38 per option for those options granted during the three months ended March 31, 2021 and 2020 respectively.

The following table summarizes stock option activity under all equity plans (excluding RSUs) during the three months ended March 31, 2021:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2020		3,682,233		$	9.10		7.84	$	37,881
Granted		1,019,365			18.90		—		—
Exercised		(11,514	)		7.58		—		—
Forfeited or cancelled		(106,944	)		13.41		—		—
Outstanding as of March 31, 2021		4,583,140		$	11.18	8.06		$	20,727
Outstanding as of March 31, 2021 - vested and expected to vest		4,583,140		$	11.18	8.06		$	20,727
Exercisable at March 31, 2021		2,097,721		$	8.11		6.90	$	13,880

As of March 31, 2021, a total of 5,549,873 shares have been authorized and reserved for issuance under all equity plans and 495,396 shares were available for future issuance under such plans.

The Company recorded share-based compensation expense related to incentive stock options, nonqualified stock options, stock grants, and stock-based awards in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2021		2020

Research and development expenses	$	840	$	496
General and administrative expenses		1,169		614
Total	$	2,009	$	1,110