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 incentive stock options, non-statutory stock options, appreciation rights, restricted stock and restricted stock units to employees, consultants and directors. 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 will be automatically increased on the first day of each calendar year during the ten-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^st of the preceding calendar year or such lesser amount as determined by our board of directors. As of September 30, 2020, an aggregate of 4,839,649 shares of common stock were available for issuance under 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. As of September 30, 2020, 4,809,187 shares and 218,500 shares of common stock were subject to outstanding options under the 2014 Plan and 2020 Plan, respectively.

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 condensed balance sheet and is reclassified to common stock and additional paid-in capital as such shares vest.

At September 30, 2020 and December 31, 2019, 22,700 and 86,409 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 September 30, 2020 and December 31, 2019 were less than $0.1 million and $0.2 million, respectively, and were recorded in other liabilities.

Activity under our 2020 Plan and 2014 Plan, which excludes options to purchase 66,982 shares granted outside of the 2020 Plan and 2014 Plan, was as follows:

				Options Outstanding
Stock Option Activity	Options Available for Grant			Number of Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Balances — December 31, 2019		835,941			3,297,586		$	1.93
Additional shares authorized		5,997,435			—
Options granted		(2,065,590	)		2,065,590		$	6.57
Options exercised		—			(263,626	)	$	1.86
Options forfeited		71,863			(71,863	)	$	2.47
Balances — September 30, 2020		4,839,649			5,027,687		$	3.83		8.22	$	228,992
Vested and expected to vest — September 30, 2020					5,027,687		$	3.83		8.22	$	228,992
Exercisable at September 30, 2020					1,782,595		$	1.85		6.70	$	84,725

During the three months ended September 30, 2020 and 2019, 67,792 and 279,947 shares of stock options, respectively, were exercised for cash at a weighted-average price per share of $1.60 and $1.55, respectively. The weighted-average grant date fair value of options granted for the three months ended September 30, 2020 and 2019 was $29.83 and $2.31, respectively. The intrinsic value of the stock options exercised was $2.5 million and $0.2 million for the three months ended September 30, 2020 and 2019, respectively.

During the nine months ended September 30, 2020 and 2019, 263,626 and 280,836 shares of stock options, respectively, were exercised for cash at a weighted-average price per share of $1.86 and $1.55, respectively. The weighted-average grant date fair value of options granted for the nine months ended September 30, 2020 and 2019 was $8.17 and $1.51, respectively. The intrinsic value of the stock options exercised was $5.1 million and $0.2 million for the nine months ended September 30, 2020 and 2019, respectively.

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. 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 will be automatically increased on the first day of each calendar year during the ten-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^st of the preceding calendar year or such lesser amount as determined by our board of directors. As of September 30, 2020, 650,000 shares of common stock were available for issuance under the 2020 ESPP.

We estimated the fair value of employee stock options using the Black-Scholes option-pricing model for the three and nine months ended September 30, 2020 and 2019 using the following weighted-average assumptions:

	Three Months Ended September 30,		Nine Months Ended September 30,
	2020	2019	2020	2019
Fair Value Assumptions
Expected volatility	93.0% - 93.5%	80.2% - 80.4%	81.2% - 93.5%	78.4% - 80.4%
Expected dividend yield	0%	0%	0%	0%
Expected term (in years)	5.6 - 5.6	6.0 - 6.1	5.6 - 6.1	5.9 - 6.1
Risk-free interest rate	0.3%	1.6% - 1.8%	0.3% - 1.4%	1.6% - 2.4%

We estimated the fair value of shares under the 2020 ESPP using the Black-Scholes option-pricing model for the three and nine months ended September 30, 2020 and 2019 using the following weighted-average assumptions:

	Three Months Ended September 30,		Nine Months Ended September 30,
	2020	2019	2020	2019
Fair Value Assumptions
Expected volatility	109.7% - 158.2%	N/A	107.0% - 158.2%	N/A
Expected dividend yield	0%	N/A	0%	N/A
Expected term (in years)	0.4 - 1.9	N/A	0.4 - 1.9	N/A
Risk-free interest rate	0.2%	N/A	0.2%	N/A

We recorded total stock-based compensation expense for the three and nine months ended September 30, 2020 and 2019 related to the 2014 Plan, the 2020 Plan and the 2020 ESPP in the condensed statements of operations and allocated the amounts as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
	(In thousands)				(In thousands)
Research and development	$	558	$	88	$	1,081	$	262
General and administrative		1,280		178		2,418		548
Total	$	1,838	$	266	$	3,499	$	810

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 nine months ended September 30, 2020.