The following table presents the amount of stock-based compensation expense related to stock-based awards on our unaudited condensed consolidated statements of operations during the periods presented:

	Three months ended						Six months ended
	June 30,						June 30,
	2020			2019			2020			2019
	(in millions)						(in millions)
Cost of revenue	$	—		$	—		$	1		$	—
Selling and marketing		4			6			7			11
Technology and content		9			14			20			27
General and administrative		12			12			23			22
Total stock-based compensation expense		25			32			51			60
Income tax benefit from stock-based compensation		(5	)		(8	)		(12	)		(14	)
Total stock-based compensation expense, net of tax	$	20		$	24		$	39		$	46

We capitalized $4 million and $8 million of stock-based compensation expense as internal-use software and website development costs during the three and six months ended June 30, 2020, respectively, and $5 million and $9 million during the three and six months ended June 30, 2019, respectively.

A summary of our stock option activity, consisting primarily of service-based non-qualified stock options, during the six months ended June 30, 2020, is presented below:

				Weighted		Weighted
				Average		Average
				Exercise		Remaining		Aggregate
	Options			Price Per		Contractual		Intrinsic
	Outstanding			Share		Life		Value
	(in thousands)					(in years)		(in millions)
Options outstanding at December 31, 2019		6,017		$	50.27
Granted		1,095			25.38
Exercised		(2	)		17.08
Cancelled or expired		(732	)		46.74
Options outstanding at June 30, 2020		6,378		$	46.42		5.8	$	—
Exercisable as of June 30, 2020		3,630		$	55.30		3.9	$	—
Vested and expected to vest after June 30, 2020 (1)		6,378		$	46.42		5.8	$	—

Aggregate intrinsic value represents the difference between the closing stock price of our common stock and the exercise price of outstanding, in-the-money options. Our closing stock price as reported on Nasdaq as of June 30, 2020 was $19.01. The total intrinsic value of stock options exercised for the six months ended June 30, 2020 and 2019 was not material and $2 million, respectively.

The fair value of stock option grants has been estimated at the date of grant using the Black–Scholes option pricing model with the following weighted average assumptions for the periods presented:

	Six months ended
	June 30,
	2020			2019
Risk free interest rate		1.18	%		2.42	%
Expected term (in years)		5.30			5.19
Expected volatility		43.13	%		42.17	%
Expected dividend yield	— %			— %
Weighted-average grant date fair value	$	10.11		$	21.80

The total fair value of stock options vested was $11 million and $10 million for the six months ended June 30, 2020 and 2019, respectively.

A summary of our RSU activity during the six months ended June 30, 2020 is presented below:

				Weighted
				Average
				Grant-		Aggregate
	RSUs			Date Fair		Intrinsic
	Outstanding			Value Per Share		Value
	(in thousands)					(in millions)
Unvested RSUs outstanding as of December 31, 2019		8,469		$	45.42
Granted		4,834			25.20
Vested and released (1)		(2,397	)		47.67
Cancelled		(2,858	)		38.00
Unvested RSUs outstanding as of June 30, 2020		8,048		$	34.96	$	153

(1) Inclusive of 628,545 RSUs withheld due to net share settlement to satisfy required employee tax withholding requirements. Potential shares which had been convertible under RSUs that were withheld under net share settlement remain in the authorized but unissued pool under the Tripadvisor, Inc. 2018 Stock and Annual Incentive Plan (the “2018 Plan”) and can be reissued by the Company. Total payments for the employees’ tax obligations to the taxing authorities due to net share settlements are reflected as a financing activity within the unaudited condensed consolidated statements of cash flows.

On May 8, 2020, the Company entered into an amended employment agreement (“Amendment”) with Ernst Teunissen, the Company’s Chief Financial Officer and Senior Vice President. The Amendment, among other things, provides for a target payment (“Bonus Award”) in an amount equal to the difference between a maximum payment of $7 million and the aggregate intrinsic value of Mr. Teunissen’s RSU and stock options that vest between May 1, 2020 and May 31, 2022 (the “Target Period”), as measured using the average market price of the Company’s common stock for ten trading days immediately prior to May 31, 2022. On a quarterly basis, management estimates the Bonus Award and accrues this amount ratably over the Target Period. As of June 30, 2020, this amount is classified in other long-term liabilities on the unaudited condensed consolidated balance sheet, and is not material. The foregoing description of the Amendment does not purport to be complete and is qualified in its entirety by reference to the full text of the Amendment filed as Exhibit 10.9 to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2020.

On May 27, 2020, the Compensation Committee of the Board of Directors, approved a modification to the Company’s annual RSU grant issued to its employees in the first quarter of 2020, which consisted of reducing the original grant-date vesting period from four years to two years. This modification resulted in the acceleration and recognition of an additional $10 million of stock-based compensation expense during the three months ended June 30, 2020, given the modified vesting term. There was no change to the original fair value of the impacted RSUs as a result of this modification. This modification did not apply to the RSU grant to Mr. Teunissen in light of the separate arrangement, as described above.

A summary of our MSU activity during the six months ended June 30, 2020 is presented below:

				Weighted
				Average
				Grant-		Aggregate
	MSUs			Date Fair		Intrinsic
	Outstanding			Value Per Share		Value
	(in thousands)					(in millions)
Unvested MSUs outstanding as of December 31, 2019		389		$	40.99
Granted (1)		133			28.15
Vested and released		―			―
Cancelled		(24	)		58.63
Unvested MSUs outstanding as of June 30, 2020		498		$	36.71	$	9

A Monte-Carlo simulation model, which simulated the present value of the potential outcomes of future stock prices and TSR of the Company and the Nasdaq Composite Total Return Index over the performance period, was used to calculate the grant-date fair

value of our MSU awards. The estimated grant-date fair value of these awards is being amortized on a straight-line basis over the requisite service period through December 31, 2022.

Total current income tax benefits associated with the exercise or settlement of Tripadvisor stock-based awards held by our employees was $1 million and $13 million during the three and six months ended June 30, 2020, respectively, and $3 million and $22 million during the three and six months ended June 30, 2019, respectively.

A summary of our remaining unrecognized stock-based compensation expense and the weighted average remaining amortization period at June 30, 2020 related to our non-vested equity awards is presented below (in millions, except in years information):