EQUITY‑BASED COMPENSATION

We currently maintain three equity compensation plans; our Fourth Amended and Restated 2007 Equity Incentive Plan, as amended (the “2007 Plan”), the Lumara Health Inc. Amended and Restated 2013 Incentive Compensation Plan (the “Lumara Health 2013 Plan”) and our 2015 Employee Stock Purchase Plan (“2015 ESPP”). All outstanding stock options granted under each of our equity compensation plans other than our 2015 ESPP have an exercise price equal to the closing price of a share of our common stock on the grant date.

Stock Options

The following table summarizes stock option activity for the three months ended March 31, 2019:



	2007 Equity		2013 Lumara		Inducement
	Plan		Equity Plan		Grants		Total
Outstanding at December 31, 2018	2,781,786		124,450		810,343		3,716,579
Granted	358,683		26,400		16,500		401,583
Exercised	(2,025	)	—		—		(2,025	)
Expired or terminated	(214,881	)	(10,613	)	(2,250	)	(227,744	)
Outstanding at March 31, 2019	2,923,563		140,237		824,593		3,888,393

Restricted Stock Units

The following table summarizes RSU activity for the three months ended March 31, 2019:



	2007 Equity		2013 Lumara	Inducement
	Plan		Equity Plan	Grants		Total
Outstanding at December 31, 2018	1,041,141		2,101	85,293		1,128,535
Granted	1,007,719		1,100	2,100		1,010,919
Vested	(309,877	)	—	(10,669	)	(320,546	)
Expired or terminated	(99,163	)	—	—		(99,163	)
Outstanding at March 31, 2019	1,639,820		3,201	76,724		1,719,745

In March 2019, we granted RSUs under our 2007 Plan to certain members of our senior management covering a maximum of 365,591 shares of common stock. These performance-based RSUs will vest, if at all, on February 24, 2022, based on our total shareholder return performance measured against the median total shareholder return of a defined group of companies over a three-year period. As of March 31, 2019, the maximum shares of common stock that may be issued under these awards is 365,591. The maximum aggregate total fair value of these RSUs is $4.7 million, which is being recognized as expense over a period of three years from the date of grant, net of any actual forfeitures.

Equity-Based Compensation Expense

Equity-based compensation expense for the three months ended March 31, 2019 and 2018 consisted of the following (in thousands):



	Three Months Ended March 31,
	2019		2018
Cost of product sales	$	202	$	200
Research and development	680		720
Selling, general and administrative	3,325		3,870
Total equity-based compensation expense	4,207		4,790
Income tax effect	—		(835		)
After-tax effect of equity-based compensation expense	$	4,207	$	3,955

In addition to the equity-based compensation expense presented in the table above, we incurred $0.7 million of equity-based compensation expense related to the restructuring activities during the three months ended March 31, 2019, which is classified within restructuring expense on our condensed consolidated statement of operations for the three months ended March 31, 2019.

We reduce the compensation expense being recognized to account for estimated forfeitures, which we estimate based primarily on historical experience, adjusted for unusual events such as corporate restructurings, which may result in higher than expected turnover and forfeitures. Under current accounting guidance, forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.