In June 2020, our board of directors adopted, and our stockholders approved, the 2020 Plan, which became effective on June 11, 2020. Under the 2020 Plan, we may grant stock options, appreciation rights, restricted stock and restricted stock units (RSUs) to employees, consultants and directors. Stock options granted under the 2020 Plan may be either incentive stock options or nonqualified stock options. Incentive stock options may be granted only to our employees, including officers and directors who are also employees. Nonqualified stock options may be granted to our employees, officers, directors, consultants and advisors. The exercise price of stock options granted under the 2020 Plan must be at least equal to the fair market value of the common stock on the date of grant, except that an incentive stock option granted to an employee who owns more than 10% of the shares of our common stock shall have an exercise price of no less than 110% of the fair value per share on the grant date and expire five years from the date of grant. The maximum term of stock options granted under the 2020 Plan is 10 years, unless subject to the provisions regarding 10% stockholders. Our stock options granted to new employees generally vest over four years at a rate of 25% upon the first anniversary of the vesting commencement date and monthly thereafter. Our other stock options granted to employees generally vest on terms consistent with stock options granted to new employees or monthly over four years from the vesting commencement date. Our RSUs granted to new employees generally vest over four years at a rate of 25% upon one year from the grant date, then 12.5% every six months thereafter. Our other RSUs granted to employees generally vest over three and a half years at a rate of 25% upon six months from the grant date, then 12.5% every six months thereafter. A total of 10,150,000 shares of common stock were approved to be initially reserved for issuance under the 2020 Plan. The number of shares that remained available for issuance under the 2014 Plan as of the effective date of the 2020 Plan, and shares subject to outstanding awards under the 2014 Plan as of the effective date of the 2020 Plan that are subsequently canceled, forfeited or repurchased by us, will be added to the shares reserved under the 2020 Plan. In addition, the number of shares of common stock available for issuance under the 2020 Plan is automatically increased on the first day of each calendar year during the 10-year term of the 2020 Plan, beginning with January 1, 2021 and ending with January 1, 2030, by an amount equal to 5% of the outstanding number of shares of our common stock on December 31 of the preceding calendar year or such lesser amount as determined by our board of directors. As of December 31, 2022, an aggregate of 4,679,598 shares of common stock were available for issuance under the 2020 Plan. Effective January 1, 2023, the number of shares of common stock available under the 2020 Plan increased by 3,973,533 shares pursuant to the evergreen provision of the 2020 Plan.

Our 2014 Plan permitted the granting of incentive stock options, non-statutory stock options, restricted stock and other stock-based awards. Subsequent to the adoption of the 2020 Plan, no additional equity awards can be made under the 2014 Plan. Shares reserved and remaining available for issuance under the 2014 Plan were added to the 2020 Plan reserve upon its effectiveness.

The terms of the 2014 Plan permit the exercise of options granted prior to vesting, subject to required approvals. The unvested shares are subject to our lapsing repurchase right upon termination of employment at the original purchase price. Shares purchased by employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules. Cash received for early exercised stock options is recorded as other liabilities on the balance sheet and is reclassified to common stock and additional paid-in capital as such shares vest.

As of December 31, 2022, 2,576,161 shares and 5,596,099 shares of common stock were subject to outstanding options and RSUs under the 2014 Plan and 2020 Plan, respectively.

At December 31, 2022 and 2021, 3,705 shares and 7,410 shares, respectively, remained subject to our right of repurchase as a result of the early exercised stock options. The remaining liabilities related to early exercised shares as of December 31, 2022 and 2021 were both less than $0.1 million and were recorded in other liabilities.

Stock option activity under our 2020 Plan and 2014 Plan, which excludes options to purchase 36,710 shares granted outside of the 2020 Plan and 2014 Plan, was as follows:


					Options Outstanding
Stock Option and Restricted Stock Units Activity	Options and RSUs Available for Grant				Number of Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Balances — December 31, 2020		4,651,149				5,121,549		$	4.99
Additional shares authorized		2,553,579				—
Options granted		(1,616,021	)			1,616,021		$	21.83
Options exercised		—				(926,514	)	$	3.25
Options forfeited		516,049				(516,049	)	$	16.70
Balances — December 31, 2021		6,104,756				5,295,007		$	9.30
Additional shares authorized		2,651,598				—
Options granted		(3,850,981	)			3,850,981		$	27.67
Options exercised		385		(1)		(1,153,285	)	$	4.25
Options forfeited		277,209				(277,209	)	$	23.54
Restricted Stock Units granted		(581,047	)
Restricted Stock Units withheld		32,626
Restricted Stock Units forfeited		45,052
Balances — December 31, 2022		4,679,598				7,715,494		$	18.70		8.20	$	225,667
Vested and expected to vest — December 31, 2022						7,715,494		$	18.70		8.20	$	225,667
Exercisable at December 31, 2022						2,921,091		$	9.41		6.81	$	112,585

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(1)

Net exercise - shares returned to the Plan.

During the years ended December 31, 2022, 2021 and 2020, 1,153,285, 926,514 and 358,264 shares of stock options, respectively, were exercised for cash at a weighted-average price per share of $4.25, $3.25 and $1.88, respectively. The weighted-average grant date fair value of options granted for the years ended December 31, 2022, 2021 and 2020 was $18.88, $14.65 and $9.62, respectively. The intrinsic value of the stock options exercised was $34.0 million, $18.9 million and $7.8 million for the years ended December 31, 2022 , 2021 and 2020, respectively.

In March 2022, our board of directors authorized the issuance of RSUs under our 2020 Plan and adopted a form of Restricted Stock Unit Grant Notice and Restricted Stock Unit Award Agreement (the "RSU Agreement"), which is intended to serve as a standard form agreement for RSU grants issued to employees. RSU activity for the year ended December 31, 2022 was as follows:

The weighted-average grant date fair value of RSUs granted during the year ended December 31, 2022 was $26.25. The aggregate fair value of unvested RSU is calculated using the closing price of our common stock on the grant date. As of December 31, 2022, the unrecognized stock-based compensation cost of unvested RSUs was $10.8 million, which is expected to be recognized over a weighted-average period of 3.0 years.

In June 2020, our board of directors adopted, and our stockholders approved, the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), which became effective on June 11, 2020. The 2020 ESPP permits participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation. Employees enrolled in the 2020 ESPP, purchase shares of common stock at a price per share equal to 85% of the lower of the fair market value at the start or end of the six-month purchase periods within the two-year offering period. A total of 650,000 shares of common stock were approved to be initially reserved for issuance under the 2020 ESPP. In addition, the number of shares of common stock available for issuance under the 2020 ESPP is automatically increased on the first day of each calendar year during the 10-year term of the 2020 Plan, beginning with January 1, 2021 and ending with January 1, 2030, by an amount of 1% of the outstanding number of shares of our common stock on December 31 of the preceding calendar year or such lesser amount as determined by our board of directors. Activity under our 2020 ESPP was as follows:

Effective January 1, 2023, the number of shares of common stock available under the 2020 ESPP increased by 794,706 shares pursuant to the evergreen provision of the 2020 ESPP.

Upon our IPO, 362,935 performance-based awards vested and, as a result, we recognized $0.3 million of stock-based compensation expense during the three months ended June 30, 2020, which amount is included in the above table for the year ended December 31, 2020.

As of December 31, 2022, there was $87.7 million of unrecognized stock-based compensation expense related to the employee and non-employee awards, which is expected to be recognized over a weighted-average period of 2.9 years.