Incentive Plans

Stock-based compensation

For the three and nine months ended September 30, 2016, the Company recorded $31 million and $84 million, respectively, of stock-based compensation expense for all plans, as compared to $26 million and $87 million for the same respective periods in 2015. As of September 30, 2016, there was $138 million of unrecognized compensation expense related to unvested share-based compensation plan awards, including $36 million attributable to stock-based awards that are expected to be settled on their vesting date in cash, rather than in equity shares ("Liability Awards"). The unrecognized compensation expense will be recognized over the remaining vesting periods of the awards, which is a period of less than three years on a weighted average basis. As of September 30, 2016 and December 31, 2015, accounts payable – due to affiliates included $17 million and $16 million, respectively, of liabilities attributable to Liability Awards.

The following table summarizes the activity that occurred during the nine months ended September 30, 2016 for each type of share-based incentive award issued by Pioneer:



	Restricted Stock Equity Awards		Restricted Stock Liability Awards		Performance Units		Stock Options
Outstanding as of December 31, 2015	1,081,650		271,031		148,547		199,058
Awards granted	520,980		180,383		104,114		—
Awards vested	(459,833	)	(141,441	)	(8,670	)	—
Awards forfeited	(43,996	)	(14,067	)	(4,821	)	—
Outstanding as of September 30, 2016	1,098,801		295,906		239,170		199,058