As of December 31, 2020, the Company’s approved equity incentive plans included the 2015 Equity Incentive Plan (“2015 Plan”), the 2013 Equity Incentive Plan (“2013 Plan”), and the 2008 Equity Incentive Plan (“2008 Plan”). These plans are administered by the Board of Directors and permit the granting of stock options, stock appreciation rights, restricted stock, restricted stock units and dividend equivalent rights (“DERs”) to employees, officers, directors and consultants of the Company.

The Company has certain stock option and restricted stock awards outstanding under each of its equity incentive plans but, upon adoption of the 2015 Plan, no longer grants new equity awards under its 2008 and 2013 Plans. The Company adopted its 2015 Plan in June 2015 and subsequently amended the plan in April 2016, 2017 and 2019 which increased the common stock reserved for issuance under the plan to an aggregate 6,580,277 shares. The Company assumed Progenics equity plans due to the acquisition as discussed in Note 1, “Description of Business”.


	Year Ended December 31,
(in thousands)	2020		2019		2018
Cost of goods sold	$	2,820	$	2,091	$	1,140
Sales and marketing	1,821		1,953		1,244
General and administrative	7,333		6,990		4,990
Research and development	2,101		1,458		1,344
Total stock-based compensation expense	$	14,075	$	12,492	$	8,718

Stock option awards under the 2015 Plan are granted with an exercise price equal to the fair value of the Company’s common stock at the date of grant. All option awards have a ten-year contractual term.


	Total Stock Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance at January 1, 2020	272,224	$	17.44
Options granted	2,027,744	$	19.44
Options exercised	(8,868)	$	8.72
Options cancelled and forfeited	(715,881)	$	19.47
Outstanding at December 31, 2020	1,575,219	$	19.03	4.8	229,390

Exercisable at December 31, 2020	1,271,041	$	19.72	3.8	228,958

All options granted during the year ended December 31, 2020 represent Replacement Stock Options issued in connection with the Progenics Acquisition, of which $7.1 million related to precombination services for awards that had vested prior to the acquisition and was recorded as a component of consideration transferred in the Progenics Acquisition. The unvested Replacement Stock Options have remaining vesting terms ranging from 0.1 years to 3.7 years and will be recognized as expense over the requisite service period. There were no options granted during the years ended December 31, 2019 and 2018.

During the years ended December 31, 2020, 2019 and 2018, 8,868, 67,558 and 192,550 options were exercised having aggregate intrinsic values of $0.1 million, $0.6 million and $2.4 million, respectively.

As of December 31, 2020, there was $1.9 million of unrecognized compensation expense related to outstanding stock options, which is expected to be recognized over a weighted-average period of 2.3 years.


	Shares	Weighted- Average Grant Date Fair Value Per Share
Nonvested balance at January 1, 2020	1,031,772	$	15.20
Granted	786,006	$	15.00
Vested	(610,804)	$	12.45
Forfeited	(99,108)	$	15.53
Nonvested balance at December 31, 2020	1,107,866	$	16.58

Restricted stock generally vest over 3 years. As of December 31, 2020, there was $11.8 million of unrecognized compensation expense related to outstanding restricted stock, which is expected to be recognized over a weighted-average period of 1.9 years.

The weighted average grant-date fair value for restricted stock granted during the fiscal years ended December 31, 2020, 2019 and 2018 was $15.00, $23.33 and $15.46 per share, respectively. The total fair value of restricted stock vested in fiscal years 2020, 2019 and 2018 was $7.6 million, $6.8 million and $4.3 million, respectively.

Performance awards vest based on the requisite service period subject to the achievement of specific financial performance targets. The Company monitors the probability of achieving the performance targets on a quarterly basis and may adjust periodic stock compensation expense accordingly. The performance targets include the achievement of internal performance targets only.


	Shares	Weighted- Average Grant Date Fair Value Per Share
Nonvested balance at January 1, 2020	226,010	$	16.62
Granted	9,767	$	16.40
Vested	(235,777)	$	16.40
Forfeited	—	$	—
Nonvested balance at December 31, 2020	—	$	—

The total fair value of the performance restricted stock vested in fiscal year 2020 was $3.9 million. Performance restricted stock awards granted in 2020 relate to the Company’s overachievement of performance targets. There were no performance restricted stock awards granted during the years ended December 31, 2019 and 2018.

During the years ended December 31, 2020, 2019 and 2018, the Company granted total stockholder return (“TSR”) Awards that include a three-year market condition where the performance measurement period is three years. Vesting of the TSR Awards is based on the Company’s level of attainment of specified TSR targets relative to the percentage appreciation of a specified index of companies for the respective three-year period and is also subject to the continued employment of the grantees. The number of shares that are earned over the performance period ranges from 0% to 200% of the initial award. The fair value of these awards are based on a Monte Carlo Simulation valuation model with the following assumptions:


	Year Ended December 31,
	2020		2019		2018
Expected volatility	53.3	%	71.7	%	84.3	%
Risk-free interest rate	0.7	%	2.4	%	2.4	%
Expected life (in years)	2.8		2.9		2.8
Expected dividend yield	—		—		—


	Shares	Weighted- Average Grant Date Fair Value Per Share
Nonvested balance at January 1, 2020	306,230	$	30.56
Granted	220,971	$	23.43
Vested	—	$	—
Forfeited	(35,430)	$	27.47
Nonvested balance at December 31, 2020	491,771	$	27.58

As of December 31, 2020, there was $6.2 million of unrecognized compensation expense related to outstanding performance restricted stock which is expected to be recognized over a weighted-average period of 1.8 years.

The weighted average grant-date fair value for TSR Awards granted during the fiscal years ended December 31, 2020, 2019 and 2018 was $23.43, $39.92 and $22.76 per share, respectively.