We have two stock plans: our 2012 Equity Incentive Plan (the “2012 Plan”) and our 2021 Equity Incentive Plan (the “2021 Plan”). The 2021 Plan is the only active stock plan. The purpose of the 2012 Plan was, and of the 2021 Plan is, to provide incentive to employees, directors, and consultants of Globus. The Plans are administered by the Board of Directors of Globus (the “Board”) or its delegates. The number, type of option, exercise price, and vesting terms are determined by the Board or its delegates in accordance with the terms of the Plans. The options granted expire on a date specified by the Board, which is generally not more than ten years from the grant date. Options granted to employees generally vest in varying installments over a four-year period.

The 2012 Plan was approved by our Board in March 2012, and by our stockholders in June 2012. The 2012 Plan terminated pursuant to its terms in 2022. Following the effectiveness of our 2021 Equity Incentive Plan, we have not issued any additional awards under the 2012 Plan; however, awards previously granted under the 2012 Plan remain outstanding and are administered by our Board of Directors under the terms and conditions of the 2012 Plan. Under the 2012 Plan, the aggregate number of shares of Class A Common stock that were able to be issued subject to options and other awards is equal to the sum of (i) 3,076,923 shares, (ii) any shares available for issuance under the 2008 Plan as of March 13, 2012, (iii) any shares underlying awards outstanding under the 2008 Plan as of March 13, 2012 that, on or after that date, are forfeited, terminated, expired or lapse for any reason, or are settled for cash without delivery of shares and (iv) starting January 1, 2013, an annual increase in the number of shares available under the 2012 Plan equal to up to 3% of the number of shares of our common and preferred stock outstanding at the end of the previous year, as determined by our Board. The number of shares that were able to be issued or transferred pursuant to incentive stock options under the 2012 Plan was limited to 10,769,230 shares. The shares of Class A Common stock covered by the 2012 Plan included authorized but unissued shares, treasury shares or shares of common stock purchased on the open market.

The 2021 Plan was approved by our Board in March 2021, and by our stockholders in June 2021. Under the 2021 Plan, the aggregate number of shares of Class A Common stock that were able to be issued subject to options and other awards is equal to the sum of (i) 2,000,000 shares, (ii) any shares available for issuance under the 2012 Plan as of June 3, 2021 and (iii) any shares underlying awards outstanding under the 2012 Plan or 2021 Plan as of June 3, 2021 that, on or after that date, are forfeited, terminated, expired or lapse for any reason, or are settled for cash without delivery of shares. The number of shares that may be issued or transferred pursuant to incentive stock options under the 2021 Plan is limited to 2,000,000 shares. The shares of Class A Common stock covered by the 2021 Plan include authorized but unissued shares, treasury shares or shares of common stock purchased on the open market.

As of March 31, 2022, pursuant to the 2021 Plan, there were 3,247,276 shares of Class A Common stock reserved and 1,333,253 shares of Class A Common stock available for future grants.

Stock option activity during the three months ended March 31, 2022 is summarized as follows:



	Option ‎Shares (thousands)	Weighted ‎average ‎exercise ‎price		Weighted ‎average ‎remaining ‎contractual ‎life (years)	Aggregate ‎intrinsic ‎value ‎(thousands)
Outstanding at December 31, 2021	9,462	$	48.01
Granted	1,339		64.24
Exercised	(184)		44.57
Forfeited	(138)		56.51
Outstanding at March 31, 2022	10,479	$	50.05	7.1	$	251,187
Exercisable at March 31, 2022	5,260	$	41.60	5.9	$	169,290
Expected to vest at March 31, 2022	5,219	$	58.57	8.4	$	81,897

The total intrinsic value of stock options exercised was $4.7 million and $10.1 million during the three months ended March 31, 2022, and 2021, respectively.

The fair value of the options was estimated on the date of the grant using a Black-Scholes option pricing model with the following assumptions:



	Three Months Ended
	March 31,
	2022			2021
Risk-free interest rate	1.46%	-	1.95%	0.40%	-	0.81%
Expected term (years)	4.8			4.8
Expected volatility		34.0%			34.0%
Expected dividend yield		—%			—%

The weighted average grant date fair value of stock options granted during the three months ended March 31, 2022, and 2021 was $20.48 and $19.26 per share, respectively.

Restricted stock unit activity during the three months ended March 31, 2022 is summarized as follows:


	Restricted Stock ‎Units (thousands)	Weighted ‎average ‎grant date fair value ‎per share		Weighted ‎average ‎remaining ‎contractual ‎life (years)
Outstanding at December 31, 2021	29	$	72.54
Granted	2		70.94
Vested	—		—
Forfeited	—		—
Outstanding at March 31, 2022	31	$	72.40	8.5

Compensation expense related to stock options granted to employees and non-employees under the Plans was as follows:



	Three Months Ended
	March 31,
(In thousands)	2022		2021
Stock-based compensation expense	$	8,152	$	7,698
Net stock-based compensation capitalized into inventory		201		185
Total stock-based compensation cost	$	8,353	$	7,883

As of March 31, 2022, there was $78.8 million of unrecognized compensation expense related to unvested employee stock options that are expected to vest over a weighted average period of approximately three years.