(14) Stock Plans:

At September 30, 2018, we have seven stock-based compensation plans under which grants were made and awards remained outstanding. No further awards may be granted under six of the plans: the 1996 Equity Incentive Plan (the 1996 EIP), the Amended and Restated 2000 Equity Incentive Plan (the 2000 EIP), the 2009 Equity Incentive Plan (the 2009 EIP), the 2013 Equity Incentive Plan (the 2013 EIP), the Deferred Fee Plan and the Directors’ Equity Plan. At September 30, 2018, there were approximately 5,667,000 shares authorized for grant and approximately 2,636,000 shares available for grant under the 2017 Equity Incentive Plan (the 2017 EIP and together with the 1996 EIP, the 2000 EIP, the 2009 EIP and the 2013 EIPS, the EIPs).

Performance Shares

On February 14, 2018, the Compensation Committee of our Board of Directors granted approximately 284,000 net performance shares under the Frontier Long Term Incentive Plan (the LTIP) and set the operating cash flow performance goal for 2018, which applies to the first year of the 2018-2020 measurement period, the second year of the 2017-2019 measurement period and the third year of the 2016-2018 measurement period.

The following summary presents information regarding LTIP target performance shares as of September 30, 2018 and changes during the nine months then ended with regard to LTIP shares awarded under the 2013 EIP and the 2017 EIP:



		Number of
		Shares
		(in thousands)
Balance at January 1, 2018		306
LTIP target performance shares granted, net		284
LTIP target performance shares earned		(18)
LTIP target performance shares forfeited		(73)
Balance at September 30, 2018		499

For purposes of determining compensation expense, the fair value of each performance share is measured at the end of each reporting period and, therefore, will fluctuate based on the price of Frontier common stock as well as performance relative to the targets. For the nine months ended September 30, 2018 and 2017, we recognized net compensation expense, reflected in “Selling, general and administrative expenses,” of $3 million and $0, respectively, for the LTIP.

Restricted Stock

The following summary presents information regarding unvested restricted stock as of September 30, 2018 and changes during the nine months then ended with regard to restricted stock granted under the 2013 EIP and the 2017 EIP:



		Weighted
		Average
	Number of	Grant Date		Aggregate
	Shares	Fair Value		Fair Value
	(in thousands)	(per share)		(in millions)
Balance at January 1, 2018	633	$	58.63	$	4
Restricted stock granted	2,023	$	8.26	$	13
Restricted stock vested	(221)	$	66.81	$	(1)
Restricted stock forfeited	(560)	$	16.32
Balance at September 30, 2018	1,875	$	16.08	$	12

For purposes of determining compensation expense, the fair value of each restricted stock grant is estimated based on the closing price of a share of our common stock on the date of the grant. Total remaining unrecognized compensation cost associated with unvested restricted stock awards that is deferred at September 30, 2018 was $28 million, and the weighted average vesting period over which this cost is expected to be recognized is approximately 2 years.

Shares of restricted stock granted during the first nine months of 2017 totaled 454,000. The total fair value of shares of restricted stock granted and vested at September 30, 2017 was approximately $5 million and $3 million, respectively. The total fair value of unvested restricted stock at September 30, 2017 was $8 million. The weighted average grant date fair value of restricted shares granted during the nine months ended September 30, 2017 was $47.77 per share.

We have granted restricted stock awards to employees in the form of our common stock. None of the restricted stock awards may be sold, assigned, pledged or otherwise transferred, voluntarily or involuntarily, by the employees until the restrictions lapse, subject to limited exceptions. The restrictions are time-based. Compensation expense, recognized in “Selling, general and administrative expenses,” of $10 million and $14 million for each of the nine month periods ended September 30, 2018 and 2017, respectively, has been recorded in connection with these grants.