18. Stock-Based Compensation and Awards

The following table presents the stock-based compensation expense included in our results of operations (in thousands):

	Years Ended December 31,
	2014		2013		2012
Stock options	$	1,714	$	2,241	$	2,552
Restricted stock, restricted stock units, performance units, cash settled restricted stock units, cash settled performance units and phantom units	25,087		20,518		16,583
Employee stock purchase plan	175		142		114
Total stock-based compensation expense	$	26,976	$	22,901	$	19,249

Stock Incentive Plan

In April 2013, we adopted the 2013 Plan to provide for the granting of stock options, restricted stock, restricted stock units, stock appreciation rights, performance units, other stock-based awards and dividend equivalent rights to employees, directors and consultants of Exterran. Under the 2013 Plan, the maximum number of shares of common stock available for issuance pursuant to awards is 6,500,000. Each option and stock appreciation right granted counts as one share against the aggregate share limit, and any share subject to a stock settled award other than a stock option, stock appreciation right or other award for which the recipient pays intrinsic value counts as 1.75 shares against the aggregate share limit. Awards granted under the 2013 Plan that are subsequently cancelled, terminated or forfeited are available for future grant. Cash settled awards are not counted against the aggregate share limit. No additional grants may be made under the 2007 Plan and the Exterran Holdings, Inc. 2011 Employment Inducement Long-Term Equity Plan (the “Employment Inducement Plan”). Previous grants made under the 2007 Plan and the Employment Inducement Plan will continue to be governed by their respective plans.

Stock Options

Stock options are granted at fair market value at the grant date, are exercisable according to the vesting schedule established by the compensation committee of our board of directors in its sole discretion and expire no later than seven years after the grant date. Stock options generally vest one-third per year on each of the first three anniversaries of the grant date.

The weighted average grant date fair value for stock options granted during the years ended December 31, 2014, 2013 and 2012 was $14.47, $10.19 and $5.74, respectively, and was estimated using the Black-Scholes option valuation model with the following weighted average assumptions:

	Years Ended December 31,
	2014		2013		2012
Expected life in years	4.5		4.5		4.5
Risk-free interest rate	1.33	%	0.66	%	0.78	%
Volatility	46.51	%	49.19	%	47.96	%
Dividend yield	1.5	%	0.0	%	0.0	%

The risk-free interest rate is based on the U.S. Treasury yield curve in effect on the grant date for a period commensurate with the estimated expected life of the stock options. Expected volatility is based on the historical volatility of our stock over the period commensurate with the expected life of the stock options and other factors. The dividend yield is based on the current annualized dividend rate in effect during the quarter in which the grant was made. At the time of the stock option grants during each of the years ended December 31, 2013 and 2012, we had not historically paid any dividends and did not expect to pay any dividends during the expected life of the stock options.

The following table presents stock option activity during the year ended December 31, 2014:

	Stock Options (in thousands)		Weighted Average Exercise Price Per Share		Weighted Average Remaining Life (in years)	Aggregate Intrinsic Value (in thousands)
Options outstanding, January 1, 2014	2,152		$	28.27
Granted	107		41.18
Exercised	(730	)	17.57
Cancelled	(34	)	73.54
Options outstanding, December 31, 2014	1,495		33.39		2.6	$	12,993
Options exercisable, December 31, 2014	1,251		33.95		2.1	11,567

Intrinsic value is the difference between the market value of our stock and the exercise price of each stock option multiplied by the number of stock options outstanding for those stock options where the market value exceeds their exercise price. The total intrinsic value of stock options exercised during 2014, 2013 and 2012 was $16.6 million, $4.4 million and $0.1 million, respectively. As of December 31, 2014, we expect $1.7 million of unrecognized compensation cost related to unvested stock options to be recognized over the weighted-average period of 1.7 years.

Restricted Stock, Restricted Stock Units, Performance Units, Cash Settled Restricted Stock Units and Cash Settled Performance Units

For grants of restricted stock, restricted stock units and performance units, we recognize compensation expense over the vesting period equal to the fair value of our common stock at the grant date. Our restricted stock and certain of our stock settled restricted stock units include nonforfeitable rights to receive dividends or dividend equivalents. We remeasure the fair value of cash settled restricted stock units and cash settled performance units and record a cumulative adjustment of the expense previously recognized. Our obligation related to the cash settled restricted stock units and cash settled performance units is reflected as a liability in our consolidated balance sheets. Restricted stock, restricted stock units, performance units, cash settled restricted stock units and cash settled performance units generally vest one-third per year on each of the first three anniversaries of the grant date.

The following table presents restricted stock, restricted stock unit, performance unit, cash settled restricted stock unit and cash settled performance unit activity during the year ended December 31, 2014:

	Shares (in thousands)		Weighted Average Grant-Date Fair Value Per Share
Non-vested awards, January 1, 2014	1,672		$	18.97
Granted	459		41.35
Vested	(897	)	18.98
Cancelled	(64	)	25.86
Non-vested awards, December 31, 2014(1)	1,170		27.37

(1)

Non-vested awards as of December 31, 2014 are comprised of 208,000 cash settled restricted stock units and cash settled performance units and 962,000 restricted shares, restricted stock units and performance units.

As of December 31, 2014, we expect $19.6 million of unrecognized compensation cost related to unvested restricted stock, restricted stock units, performance units, cash settled restricted stock units and cash settled performance units to be recognized over the weighted-average period of 1.7 years.

Employee Stock Purchase Plan

In August 2007, we adopted the Exterran Holdings, Inc. Employee Stock Purchase Plan (“ESPP”), which is intended to provide employees with an opportunity to participate in our long-term performance and success through the purchase of shares of common stock at a price that may be less than fair market value. The ESPP is designed to comply with Section 423 of the Internal Revenue Code of 1986, as amended. Each quarter, an eligible employee may elect to withhold a portion of his or her salary up to the lesser of $25,000 per year or 10% of his or her eligible pay to purchase shares of our common stock at a price equal to 85% to 100% of the fair market value of the stock as of the first trading day of the quarter, the last trading day of the quarter or the lower of the first trading day of the quarter and the last trading day of the quarter, as the compensation committee of our board of directors may determine. The ESPP will terminate on the date that all shares of common stock authorized for sale under the ESPP have been purchased, unless it is extended. In May 2011, we amended the ESPP to increase the maximum number of shares of common stock available for purchase under the ESPP to 1,000,000. At December 31, 2014, 188,049 shares remained available for purchase under the ESPP. Our ESPP is compensatory and, as a result, we record an expense in our consolidated statements of operations related to the ESPP. The purchase discount under the ESPP is 5% of the fair market value of our common stock on the first trading day of the quarter or the last trading day of the quarter, whichever is lower.

Directors’ Stock and Deferral Plan

On August 20, 2007, we adopted the Exterran Holdings, Inc. Directors’ Stock and Deferral Plan to provide non-employee members of the board of directors with an opportunity to elect to receive our common stock as payment for a portion or all of their retainer and meeting fees. The number of shares paid each quarter is determined by dividing the dollar amount of fees elected to be paid in common stock by the closing sales price per share of the common stock on the last day of the quarter. In addition, directors who elect to receive a portion or all of their fees in the form of common stock may also elect to defer, until a later date, the receipt of a portion or all of their fees to be received in common stock. We have reserved 100,000 shares under the Directors’ Stock and Deferral Plan, and as of December 31, 2014, 54,847 shares remain available to be issued under the plan.

Partnership Long-Term Incentive Plan

The Partnership’s Long-Term Incentive Plan (the “Partnership Plan”) was adopted, in October 2006 for employees, directors and consultants of the Partnership, us and our respective affiliates. A maximum of 1,035,378 common units, common unit options, restricted units and phantom units are available under the Partnership Plan. The Partnership Plan is administered by the board of directors of Exterran GP LLC, the general partner of the Partnership’s general partner, or a committee thereof (the “Partnership Plan Administrator”).

Phantom units are notional units that entitle the grantee to receive a common unit upon the vesting of a phantom unit or, at the discretion of the Partnership Plan Administrator, cash equal to the fair market value of a common unit. Phantom units granted under the Partnership Plan may include nonforfeitable tandem distribution equivalent rights to receive cash distributions on unvested phantom units in the quarter in which distributions are paid on common units. Phantom units generally vest one-third per year on each of the first three anniversaries of the grant date.

Partnership Phantom Units

The following table presents phantom unit activity during the year ended December 31, 2014:

	Phantom Units (in thousands)		Weighted Average Grant-Date Fair Value per Unit
Phantom units outstanding, January 1, 2014	85		$	23.72
Granted	55		30.50
Vested	(48	)	24.47
Phantom units outstanding, December 31, 2014	92		27.38

As of December 31, 2014, we expect $1.6 million of unrecognized compensation cost related to unvested phantom units to be recognized over the weighted-average period of 1.8 years.