Employee stock-based compensation expense, net of the amount capitalized in internally developed software, is as follows (in thousands):

(a)

Includes expense recognized and costs capitalized in connection with the awards granted to booj employees and former owners at the time of acquisition.

(b)

Expense recognized for performance-based awards is re-assessed each quarter based on expectations of achievement against the performance conditions. As of June 30, 2019, certain conditions were no longer deemed probable of being met, primarily for awards that must achieve a certain amount of revenue over a three-year performance period, and the cumulative expense previously recognized was reversed in the current period.

(c)

In 2019, the Company revised its annual bonus plan so that a portion of the bonus for most employees will be settled in shares if the Company meets certain performance metrics. The share amounts to be issued will be determined based on the stock price at the time of vesting in early 2020. These amounts are recognized as “Accrued liabilities” in the accompanying Condensed Consolidated Balance Sheet and are not included in “Additional paid-in capital” until shares are issued.

Time-based Restricted Stock Units

The following table summarizes equity-based compensation activity related to time-based RSUs as of and for the six months ended June 30, 2019:


	Time-based restricted stock units	Weighted average grant date fair value per share
Balance, January 1, 2019	298,610	$	51.97
Granted	158,342	$	38.61
Shares vested (including tax withholding) ^(a)	(66,918)	$	46.66
Forfeited	(5,844)	$	46.41
Balance, June 30, 2019	384,190	$	47.48

(a)

Pursuant to the terms of the 2013 Incentive Plan, RSUs withheld by the Company for the payment of the employee's tax withholding related to an RSU vesting are added back to the pool of shares available for future awards.

At June 30, 2019, there was $13.2 million of total unrecognized time-based RSU expense, all of which is related to unvested awards. This compensation expense is expected to be recognized over the weighted-average remaining vesting period of 2.15 years for time-based restricted stock units.

Performance-based Restricted Stock Units

The following table summarizes equity-based compensation activity related to performance-based RSUs as of and for the six months ended June 30, 2019:


	Performance-based restricted stock units	Weighted average grant date fair value per share
Balance, January 1, 2019	179,615	$	55.75
Granted ^(a)	93,028	$	41.37
Shares vested	(5,620)	$	56.59
Forfeited	(30,716)	$	52.97
Balance, June 30, 2019	236,307	$	39.24

(a)	Represents the total participant target award.

At June 30, 2019, there was $4.3 million of total unrecognized performance-based RSU expense, all of which is related to unvested awards. This compensation expense is expected to be recognized over the weighted-average remaining vesting period of 2.06 years for performance-based RSUs.

After giving effect to all outstanding awards (assuming maximum achievement of performance goals for performance-based awards), there were 2,187,446 additional shares available for the Company to grant as of June 30, 2019.