NOTE O — EQUITY-BASED COMPENSATION

We have various equity incentive compensation plans that provide for the granting of restricted common stock, options for the purchase of our common stock, and other performance-based, equity-based compensation awards to our executive officers, key employees, nonexecutive officers, and directors. Stock options are exercisable for periods of up to ten years. Compensation cost for all share-based payments is based on the grant date fair value and is recognized in earnings over the requisite service period. Total equity-based compensation expense, before tax, for the three years ended December 31, 2018, 2017, and 2016, was $7.4 million, $7.8 million, and $13.7 million, respectively, and is included in general and administrative expense. Total equity-based compensation expense, net of taxes, for the three years ended December 31, 2018, 2017, and 2016, was $5.8 million, $5.0 million, and $9.5 million, respectively.

Stock Incentive Plans

In May 2007, our stockholders approved the adoption of the TETRA Technologies, Inc. 2007 Equity Incentive Compensation Plan. In May 2008, our stockholders approved the adoption of the TETRA Technologies, Inc. Amended and Restated 2007 Equity Incentive Compensation Plan, which among other changes, resulted in an increase in the maximum number of shares authorized for issuance. In May 2010, our stockholders approved further amendments to the TETRA Technologies, Inc. Amended and Restated 2007 Equity Incentive Compensation Plan (renamed as the 2007 Long Term Incentive Compensation Plan) which, among other changes, resulted in an additional increase in the maximum number of shares authorized for issuance. Pursuant to the 2007 Long Term Incentive Compensation Plan, we are authorized to grant up to 5,590,000 shares in the form of stock options (including incentive stock options and nonqualified stock options); restricted stock; bonus stock; stock appreciation rights; and performance awards to employees, and non-employee directors. As of February 2017, no further awards may be granted under the TETRA Technologies, Inc. Amended and Restated 2007 Equity Incentive Compensation Plan.

In May 2011, our stockholders approved the adoption of the TETRA Technologies, Inc. 2011 Long Term Incentive Compensation Plan. Pursuant to this plan, we were authorized to grant up to 2,200,000 shares in the form of stock options, restricted stock, bonus stock, stock appreciation rights, and performance awards to employees, and non-employee directors. On May 3, 2013, shareholders approved the TETRA Technologies, Inc. 2011 Long Term Incentive Compensation Plan that, among other things, increased the number of authorized shares to 5,600,000. On May 3, 2016, shareholders approved the TETRA Technologies, Inc. Third Amended and Restated 2011 Long Term Incentive Compensation Plan which, among other things, increased the number of authorized shares to 11,000,000. As of May 2018, no further awards may be granted under the TETRA Technologies, Inc. Third Amended and Restated 2011 Long Term Incentive Compensation Plan.

In June 2011, the Compressco Partners, L.P. 2011 Long Term Incentive Plan ("CCLP Long Term Incentive Plan") was adopted by the board of directors of CCLP’s general partner. The CCLP Long Term Incentive Plan provides for grants of restricted units, phantom units, unit awards and other unit-based awards up to a plan maximum of 1,537,122 common units. On November 28, 2018, unitholders approved the CSI Compressco LP Second Amended and Restated 2011 Long Term Incentive Plan that, among other things, increased the number of authorized units to 5,037,122.

In February 2018, the board of directors adopted the 2018 Inducement Restricted Stock Plan (“2018 Inducement Plan”). The 2018 Inducement Plan provides for grants of restricted stock up to a plan maximum of 1,000,000 shares.

In May 2018, our stockholders approved the adoption of the TETRA Technologies, Inc. 2018 Equity Incentive Plan (“2018 Equity Plan”). Pursuant to this plan, we were authorized to grant up to 6,635,000 shares in the form of stock options, restricted stock, restricted stock units, bonus stock, stock appreciation rights, performance units, performance awards, other stock-based awards and cash-based awards to employees and non-employee directors.

In May 2018, our stockholders approved the adoption of the TETRA Technologies, Inc. 2018 Non-Employee Director Equity Incentive Plan (“2018 Director Plan”). Pursuant to this plan, we were authorized to grant up to 335,000 shares in the form of nonqualified stock options, stock appreciation rights, restricted stock, restricted stock units, other stock‑based awards and cash-based awards to non-employee directors.

Grants of Equity Awards by CCLP

During each of the three years ended December 31, 2018, CCLP granted restricted unit, phantom unit, or performance phantom unit awards to certain employees, officers, and directors of its general partner or of our employees. Awards of restricted units and phantom units generally vest over a three year period. Awards of performance phantom units cliff vest at the end of a performance period and are settled based on achievement of related performance measures over the performance period. Phantom units are notional units that entitle the grantee to receive a common unit upon the vesting of the award. Each of the phantom unit and performance phantom unit awards includes distribution equivalent rights that enable the recipient to receive additional units equal in value to the accumulated cash distributions made on the units subject to the award from the date of grant. Accumulated distributions associated with each underlying unit are payable upon settlement of the related phantom unit award (and are forfeited if the related award is forfeited).

The following is a summary of CCLP’s equity award activity for the year ended December 31, 2018:



	Units		Weighted Average Grant Date Fair Value Per Unit
	(In Thousands)
Nonvested units outstanding at December 31, 2017	469		$	9.31
Units granted⁽¹⁾	330		7.33
Units canceled	(186	)	8.96
Units vested	(121	)	12.37
Nonvested units outstanding at December 31, 2018⁽²⁾	492		$	7.36


(1)	The number excludes 93,996 performance-based phantom units, which represents the additional number of common units that would be issued if the maximum level of performance under the awards is achieved.

(2) The number of units granted shown above excludes 15,422 performance-based phantom units, which, when combined with the 93,996 granted (net of 2018 forfeitures), represents the maximum number of common units that would be issued if the maximum level of performance under the awards is achieved. The number of units actually issued under the awards may range from zero to 218,836.

Stock Options

The weighted average fair value of options granted during the years ended December 31, 2018, 2017, and 2016, was $1.88, $2.01, and $3.16, respectively, using the Black-Scholes option valuation model with the following weighted average assumptions:



	Year Ended December 31,
	2018	2017	2016
Expected stock price volatility	57%	53%	52%
Expected life of options	4.5 years	4.5 years	4.6 years
Risk free interest rate	2.6%	1.8%	1.2%
Expected dividend yield	—	—	—

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, 2018, 2017 and 2016, 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 is a summary of stock option activity for the year ended December 31, 2018:



	Shares Under Option		Weighted Average Option Price Per Share		Weighted-Average Remaining Contractual Life	Aggregate Intrinsic Value (in thousands)
	(In Thousands)
Outstanding at January 1, 2018	5,217		$	8.59
Options granted	791		3.89
Options canceled	(922	)	6.97
Options exercised	(66	)	3.78
Options expired	(540	)	$	21.16
Outstanding at December 31, 2018	4,480		$	6.65	5.9	$	—
Expected to vest at December 31, 2018	4,480		$	6.65	5.9	$	—
Exercisable at December 31, 2018	3,324		$	7.48	4.9	$	—

Intrinsic value is the difference between the market value of our 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 December 31, 2018, 2017, and 2016, was approximately $0.1 million, $0.0 million, and $0.1 million, respectively.

At December 31, 2018, total unrecognized compensation cost related to unvested stock options of

$1.8 million is expected to be recognized over a weighted-average remaining service period of 1.50 years.

Restricted Stock

Restricted stock awards are periodically granted to key employees, including grants for employment inducements, as well as to members of our Board of Directors. Employee awards provide for vesting periods ranging from three to five years. Non-employee director grants vest in full before the first anniversary of the grant. Upon vesting of these grants, shares are issued to award recipients. The following is a summary of activity for our outstanding restricted stock awards for the year ended December 31, 2018:



	Shares		Weighted Average Grant Date Fair Value Per Share
	(In Thousands)
Nonvested restricted shares outstanding at December 31, 2017	1,036		$	5.06
Granted	2,509		3.72
Vested	(657	)	4.93
Canceled/Forfeited	(309	)	4.68
Nonvested restricted shares outstanding at December 31, 2018	2,579		$	3.84

Total compensation cost recognized for restricted stock awards was $4.9 million, $4.0 million, and $8.4 million for the years ended December 31, 2018, 2017, and 2016, respectively. Total unrecognized compensation cost at December 31, 2018, related to restricted stock awards is approximately $6.9 million which is expected to be recognized over a weighted-average remaining amortization period of 1.95 years. During the years ended December 31, 2018, 2017, and 2016, the total fair value of shares vested was $3.2 million, $4.8 million and $8.4 million, respectively.

During 2018, 2017, and 2016, we received 79,476, 101,669 and 254,858 shares, respectively, of our common stock related to the vesting of certain employee restricted stock. Such surrendered shares received by us are included in treasury stock. At December 31, 2018, net of options previously exercised pursuant to our various equity compensation plans, we have a maximum of 6,373,059 shares of common stock issuable pursuant to awards previously granted and outstanding and awards authorized to be granted in the future.