M. EQUITY‑BASED COMPENSATION

We currently maintain four equity compensation plans, namely our Third Amended and Restated 2007 Equity Incentive Plan, as amended (the “2007 Plan”), our Amended and Restated 2000 Stock Plan (the “2000 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 (discussed below) have an exercise price equal to the closing price of a share of our common stock on the grant date.

Our 2007 Plan was originally approved by our stockholders in November 2007, and succeeded our 2000 Plan, under which no further grants may be made. Any shares that remained available for issuance under the 2000 Plan as of the date of adoption of the 2007 Plan are included in the number of shares that may be issued under the 2007 Plan. Any shares subject to outstanding awards granted under the 2000 Plan that expire or terminate for any reason prior to exercise will be added to the total number of shares of our stock available for issuance under the 2007 Plan. The total number of shares issuable pursuant to awards under this plan is 6,215,325. As of March 31, 2016, there were 1,048,949 shares remaining available for issuance under the 2007 Plan, which excludes shares subject to outstanding awards under the 2000 Plan. All outstanding options under the 2007 Plan have either a seven or ten-year term and all outstanding options under the 2000 Plan have a ten-year term.

In November 2014, we assumed the Lumara Health 2013 Plan in connection with the acquisition of Lumara Health. The total number of shares issuable pursuant to awards under this plan as of the effective date of the acquisition and after taking into account any adjustments as a result of the acquisition, was 200,000 shares. As of March 31, 2016, there were 74,219 shares remaining available for issuance under the Lumara Health 2013 Plan, which are available for grants to certain employees, officers, directors, consultants, and advisors of AMAG and our subsidiaries who are newly-hired or who previously performed services for Lumara Health. All outstanding options under the Lumara Health 2013 Plan have a ten-year term.

In May 2015, our stockholders approved our 2015 ESPP, which authorizes the issuance of up to 200,000 shares of our common stock to eligible employees. The terms of the 2015 ESPP permit eligible employees to purchase shares (subject to certain plan and tax limitations) in semi-annual offerings through payroll deductions of up to an annual maximum of 10% of the employee’s “compensation” as defined in the 2015 ESPP. Shares are purchased at a price equal to 85% of the fair market value of our common stock on either the first or last business day of the offering period, whichever is lower. Plan periods consist of six-month periods typically commencing June 1 and ending November 30 and commencing December 1 and ending May 31. As of March 31, 2016, no shares have been issued under our 2015 ESPP.

During the three months ended March 31, 2016, we also granted equity through inducement grants outside of these plans to certain employees to induce them to accept employment with us (collectively, “Inducement Grants”). The options were granted at an exercise price equal to the fair market value of a share of our common stock on the respective grant dates and will be exercisable in four equal annual installments beginning on the first anniversary of the respective grant dates. The RSU grants will vest in three equal annual installments beginning on the first anniversary of the respective grant dates. The foregoing grants were made pursuant to inducement grants outside of our stockholder approved equity plans as permitted under the NASDAQ Stock Market listing rules. We assessed the terms of these awards and determined there was no possibility that we would have to settle these awards in cash and therefore, equity accounting was applied.

Stock Options

The following table summarizes stock option activity for the three months ended March 31, 2016:


	2007 Equity	2000 Equity	2013 Lumara	Inducement
	Plan	Plan	Equity Plan	Grants	Total
Outstanding at December 31, 2015	1,963,162	14,040	96,000	830,975	2,904,177
Granted	334,000	—	—	45,000	379,000
Exercised	(25,315)	—	—	—	(25,315)
Expired or terminated	(96,878)	—	(30,000)	(38,000)	(164,878)
Outstanding at March 31, 2016	2,174,969	14,040	66,000	837,975	3,092,984

Restricted Stock Units

The following table summarizes RSU activity for the three months ended March 31, 2016:


	2007 Equity	2000 Equity	2013 Lumara	Inducement
	Plan	Plan	Equity Plan	Grants	Total
Outstanding at December 31, 2015	446,330	—	52,350	155,675	654,355
Granted	599,300	—	—	32,000	631,300
Vested	(175,971)	—	(16,749)	(5,000)	(197,720)
Expired or terminated	(36,364)	—	(4,235)	(2,500)	(43,099)
Outstanding at March 31, 2016	833,295	—	31,366	180,175	1,044,836

Equity‑based compensation expense

Equity‑based compensation expense for the three months ended March 31, 2016 and 2015 consisted of the following (in thousands):


	Three Months Ended March 31,
	2016		2015
Cost of product sales	$	320	$	41
Research and development		756		478
Selling, general and administrative		5,084		2,149
Total equity-based compensation expense	$	6,160	$	2,668
Income tax effect		(1,674)		(1,035)
After-tax effect of equity-based compensation expense	$	4,486	$	1,633

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.

We have not recognized any excess tax benefits from equity-based compensation in additional paid-in capital because the excess tax benefits have not yet reduced cash taxes paid. Accordingly, there was no impact recorded in cash flows from financing activities or cash flows from operating activities as reported in the accompanying condensed consolidated statements of cash flows.