Stock-based compensation expense for the years ended December 31, 2021 and 2020 was classified in the consolidated statements of operations as follows:


	Year Ended December 31,
	2021		2020
	(000's)
Research and development	$	658	$	605
General and administrative		3,371		3,411
Total	$	4,029	$	4,016

Prior to the Merger, Compass Therapeutics LLC maintained an incentive pool of unit-based awards that were granted to board members, employees and consultants and accounted for as unit-based compensation. Upon consummation of the Merger, all outstanding vested profit interest units were converted into shares of the Company’s common stock. Unvested units were converted into restricted shares of the Company’s common stock and will continue to vest under the same terms as the original profit interest units.

A summary of the Company’s restricted share activity during the years ended December 31, 2021 and 2020 is as follows:


	Shares (000's)			Estimated Fair Value Per Share
Unvested, December 31, 2019		2,039		$	2.04
Granted		1		$	2.34
Vested		(474	)	$	1.66
Forfeited or canceled		(670	)	$	1.75
Unvested, December 31, 2020		896		$	2.46
Granted		—		$	—
Vested		(359	)	$	1.83
Forfeited or canceled		(66	)	$	1.70
Unvested, December 31, 2021		471		$	1.76

The weighted average grant date fair value for unvested restricted stock as of December 31, 2021 was $1.76 per share. No restricted share awards have been granted following the Merger. As of December 31, 2021, remaining unrecognized compensation cost related to restricted stock awards

to be recognized in future periods totaled $0.8 million, which is expected to be recognized over a weighted average period of 1.8 years.

No restricted share awards were granted for the year ended December 31, 2021. For the year ended December 31, 2020, the fair value of each restricted stock award was estimated on the date of grant using the weighted average assumptions in the table below:

In June 2020, the Company’s board of directors adopted the 2020 Plan and reserved 2.9 million shares of common stock for issuance under this plan. The 2020 Plan provides that the number of shares reserved and available for issuance under the 2020 Plan will automatically increase each January 1, beginning on January 1, 2021, by the lesser of (i) 4% of the outstanding number of shares of our common stock on the immediately preceding December 31 or (ii) such number of shares as determined by the plan administrator no later than the immediately preceding December 31. As of December 31, 2021, 156 thousand shares remain available for future grant. On January 1, 2022, an additional 4.05 million shares became available for issuance based on 4% of the outstanding shares of common stock, for a total of 4.21 million shares available for issuance.

The 2020 Plan authorizes the board of directors or a committee of the board to grant incentive stock options, nonqualified stock options, restricted stock awards and restricted stock units ("RSUs") to eligible officers, employees, consultants and directors of the Company. Options generally vest over a period of four years and have a contractual life of ten years from the date of grant.

The following table summarizes the stock option activity for the 2020 Plan:


	Number of Nonvested Options (000's)			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (000's)
Outstanding at December 31, 2019		—		$	—			$	—
Granted		2,175		$	5.00			$	—
Exercise		-		$	—			$	—
Forfeited/cancelled		(16	)	$	5.00			$	—
Outstanding at December 31, 2020		2,159		$	5.00		9.69	$	—
Granted		1,822		$	5.02		9.27	$	—
Exercise		—		$	—		—	$	—
Forfeited/cancelled		(322	)	$	5.00		—	$	—
Outstanding at December 31, 2021		3,659		$	5.01		8.98	$	—
Vested at December 31, 2021		1,378		$	4.99		8.67	$	—

For the year ended December 31, 2021, the weighted average grant date fair value for options granted was $5.01. There was no aggregate intrinsic value for options vested and outstanding as

of December 31, 2021. As of December 31, 2021, the unrecognized compensation cost related to outstanding options was $7.1 million, expected to be recognized over a weighted average period of approximately 2.8 years.

The weighted average assumptions used in the Black-Scholes option pricing model to determine the fair value of stock options granted to employees and directors during the year ended December 31, 2021 were as follows:


	Year Ended December 31,
	2021			2020
Expected term (in years)	6.1			5.5
Risk-free rate		0.85	%		0.29	%
Expected volatility		91	%		86	%

RSUs:

The following table summarizes the RSU activity for the 2020 Plan:


	Shares (000's)		Weighted Average Price Per Share		Weighted Average Fair Value (000's)
Unvested, December 31, 2020		—	$	—	$	—
Granted		1,200	$	3.83	$	4,596
Vested		—		—		—
Forfeited or canceled		—		—		—
Unvested, December 31, 2021		1,200	$	3.83	$	4,596

Weighted average price per share is the weighted grant price based on the closing market price of each of the stock grants. The weighted average fair value is the weighted average share price times the number of shares.

As of December 31, 2021, remaining unrecognized compensation cost related to RSUs to be recognized in future periods totaled $4.4 million, which is expected to be recognized over a weighted average period of 3.9 years.