We issue equity-based awards to our employees pursuant to the 2017 Omnibus Incentive Plan (“2017 Employee Plan”) and our non-employee directors pursuant to the 2017 Stock Plan for Non-Employee Directors (“2017 Director Plan”). The 2017 Employee Plan provides that a maximum of 8,000,000 shares of our common stock may be issued, and as of March 31, 2020, 4,490,773 shares of common stock remain available for future issuance. The 2017 Director Plan provides that a maximum of 450,000 shares of our common stock may be issued, and as of March 31, 2020, 276,521 shares of common stock remain available for future issuance. For the three months ended March 31, 2020 and 2019, we recognized $2 million and $4 million of share-based compensation expense, respectively. As of March 31, 2020, unrecognized compensation expense was $28 million, which is expected to be recognized over a weighted-average period of 2.1 years. The total fair values of shares vested during the three months ended March 31, 2020 and 2019 were $17 million and $15 million, respectively.

Restricted Stock Awards (“RSAs”) generally vest in annual installments between one and three years from each grant date. The following table provides a summary of RSAs for the three months ended March 31, 2020:

	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested at January 1, 2020		557,245			29.10
Granted		468,468			22.59
Vested		(238,773	)		26.41
Forfeited		(57,361	)		29.23
Unvested at March 31, 2020		729,579		$	25.79

Performance Stock Units (“PSUs”) generally vest at the end of a three-year performance period and are subject to the achievement of a market condition based on a measure of our total shareholder return relative to the total shareholder return of the companies that comprise the FTSE Nareit Lodging Resorts Index (that have a market capitalization in excess of $1 billion as of the first day of the applicable performance period). The number of PSUs that may become vested ranges from zero to 200% of the number of PSUs granted to an employee, based on the level of achievement of the foregoing measure.

Additionally, in February 2020, we granted special awards with a one-year performance period that are subject to the achievement of a total shareholder return similar to the three-year awards, and, in addition, are subject to the achievement of a performance condition for certain cost synergies associated with the Merger. The number of PSUs that may become vested are zero if neither goal is achieved, 100% if one performance goal is achieved and 200% if both goals are achieved.

The following table provides a summary of PSUs for the three months ended March 31, 2020:

	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested at January 1, 2020		574,797			32.82
Granted		605,535			24.93
Vested		(456,121	)		32.39
Forfeited		(52,114	)		33.14
Unvested at March 31, 2020		672,097		$	25.98

The grant date fair values of the awards that are subject to the achievement of market conditions based on total shareholder return were determined using a Monte Carlo simulation valuation model with the following assumptions:

Expected volatility⁽¹⁾	22.0% - 23.0%
Dividend yield⁽²⁾		—
Risk-free rate	1.2% - 1.5%
Expected term	1 - 3 years

As of March 31, 2020, the achievement of the performance condition associated with the special one-year awards was not probable and thus no compensation expense was recognized for the three months ended March 31, 2020.