Stock Plans

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

On December 26, 2006, the Company adopted the 2006 Equity Incentive Plan, which was amended by the board of directors on November 15, 2012 (the “2006 Plan”). The 2006 Plan allowed for the granting of incentive stock options (“ISOs”) and non-qualified stock options (“NSOs”) to the employees, members of the board of directors and consultants of the Company. ISOs were granted only to the Company’s employees, including officers and directors who are also employees. NSOs were granted to employees and consultants. In July 2014, the Company’s board of directors and its stockholders approved the establishment of the 2014 Equity Incentive Award Plan (the “2014 Plan”). Options may no longer be issued under the 2006 Plan after July 30, 2014. In addition, the 2014 Plan provides for annual increases in the number of shares available for issuance thereunder on the first business day of each fiscal year, beginning with the year ended December 31, 2015, equal to four percent (4%) of the number of shares of the Company’s common stock outstanding as of such date or a lesser number of shares as determined by the Company’s board of directors.

In October 2017, the Company adopted the 2017 Inducement Plan (the “Inducement Plan”). The Company reserved 600,000 shares for issuance pursuant to stock options and RSUs under the Inducement Plan. The only persons eligible to receive grants of stock options and RSUs under Inducement Plan are individuals who satisfy the standards for inducement grants under Nasdaq guidance that is, generally, a person not previously an employee or director of Adverum, or following a bona fide period of non-employment, as an inducement material to the individual's entering into employment with Adverum.

The 2006 Plan, 2014 Plan and Inducement Plan are referred to collectively as the Plans. As of December 31, 2022, a total of 37,900,792 shares of common stock were reserved for issuance and 3,202,937 shares were available for future grants under the Plans.

Stock Options

Stock options under the 2014 Plan and the Inducement Plan may be granted for periods of up to 10 years and at prices no less than 100% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided, however, that the exercise price of an ISO and NSO granted to a 10% stockholder may not be less than 110% of the estimated fair value of the shares on the date of grant. Stock options granted to employees and non-employees generally vest ratably over four years.

The following table summarizes stock option activity under the Company’s stock plans and related information:


(In thousands, except exercise prices and years)	Options Outstanding	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Life (in years)	Aggregate Intrinsic Value (a)




Balance at December 31, 2020	10,432	$	7.19	8.2	$	31,626
Granted	8,231	7.04
Exercised	(9)	5.86
Cancelled/forfeited	(5,366)	10.32
Balance at December 31, 2021	13,288	$	5.83	6.9	$	145
Granted	10,933	1.24
Exercised	(15)	0.19
Cancelled/forfeited	(4,886)	5.29
Balance at December 31, 2022	19,320	$	3.38	8.0	$	29
Vested and expected to vest as of December 31, 2022	19,320	$	5.79	8.0	$	29
Exercisable at December 31, 2022	6,102	$	11.03	6.4	$	29

(a)The aggregate intrinsic value is calculated as the difference between the stock option exercise price and the closing price of the Company’s common stock as quoted on a national exchange.

The total intrinsic value of stock options exercised during the years ended December 31, 2022 and 2021 was $18,000 and $0.1 million, respectively.

Options granted during the year ended December 31, 2022 include 2.5 million shares of performance-based stock options with both performance and service vesting conditions.

The fair value of each stock option issued was estimated at the date of grant using the Black-Scholes valuation model with the following weighted-average assumptions:


	Options		Employee Stock Purchase Plan
	Years ended December 31,		Years ended December 31,
	2022	2021		2022	2021
Expected volatility	89%	91%		77%	122%
Expected term (in years)	6.0	6.0		1.2	1.2
Expected dividend yield	—	—		—	—
Risk-free interest rate	2.6%	1.0%		3.0%	0.1%

The weighted-average fair values of options granted during the years ended December 31, 2022 and 2021 were $0.93 and $5.18, respectively.

As of December 31, 2022, there was $30.4 million of unrecognized stock-based compensation expense related to stock options that is expected to be recognized over a weighted-average period of 2.6 years.

RSUs

RSUs are share awards that entitle the holder to receive freely tradable shares of the Company’s common stock upon vesting. The fair value of RSUs is based upon the closing sales price of the Company’s common stock on the grant date. RSUs granted to employees generally vest over a 2–4 year period.

The following table summarizes the RSU activity under the Company’s stock plans and related information:


(In thousands, except grant date fair value and years)	Number of Units	Weighted- Average Grant Date Fair Value		Weighted- Average Remaining Contractual Term (in years)




Balance at December 31, 2020	540	$	6.41	0.8
Granted	2,585	3.90
Vested and released	(305)	5.26
Forfeited	(694)	5.68
Balance at December 31, 2021	2,126	3.76		1.4
Granted	857	1.43
Vested and released	(835)	3.41
Forfeited	(455)	3.21
Balance at December 31, 2022	1,693	$	2.90	1.2

RSUs granted during the year ended December 31, 2022 include 0.4 million shares of performance stock units with both performance and service vesting conditions.

During the years ended December 31, 2022 and 2021, total fair value of RSUs vested was $2.8 million and $1.6 million, respectively. The number of RSUs vested includes shares of common stock that the Company withheld on behalf of employees or sold to cover to satisfy the minimum statutory tax withholding requirements. As of December 31, 2022, there was $1.6 million of unrecognized compensation cost related to unvested RSUs that is expected to be recognized over a weighted-average period of 1.5 years.

ESPP

In July 2014, the Company approved the establishment of the 2014 Employee Stock Purchase Plan (the “ESPP”). The Company reserved 208,833 shares of its common stock for issuance and provided for annual increases in the number of shares available for issuance on the first business day of each fiscal year, beginning in 2015, equal to the lesser of one percent (1%) of the number of the Company’s common stock shares outstanding as of such date or a number of shares as determined by the Company’s board of directors. During the year ended December 31, 2022, 887,061 shares were issued under the ESPP. As of December 31, 2022, a total of 7,043,481 shares of common stock were available for future issuance under the ESPP. As of December 31, 2022, there was $0.6 million of unrecognized compensation cost related to the ESPP.

Stock-Based Compensation Recognized in the Consolidated Statement of Operations and Comprehensive Loss

The following table presents the Company’s stock-based compensation expense:


	Years ended December 31,
	2022		2021
	(In thousands)
Research and development	$	7,108	$	8,875
General and administrative	12,971		16,319
Total share-based compensation expense	$	20,079	$	25,194

During the year ended December 31, 2021, the Company recorded approximately $1.6 million of stock‑based compensation expense as a result of the modification of the vesting and exercisability of stock awards associated with the departure of certain of its executives and directors.