13. STOCK-BASED INCENTIVE PLANS

We are externally managed by our Manager and do not currently have any employees. However, as of March 31, 2018, our Manager, certain individuals employed by an affiliate of our Manager, and certain members of our board of directors were compensated, in part, through the issuance of stock-based instruments.

We had stock-based incentive awards outstanding under seven benefit plans as of March 31, 2018: (i) our amended and restated 1997 non-employee director stock plan, or 1997 Plan; (ii) our 2007 long-term incentive plan, or 2007 Plan; (iii) our 2011 long-term incentive plan, or 2011 Plan; (iv) our 2013 stock incentive plan, or 2013 Plan; (v) our 2013 manager incentive plan, or 2013 Manager Plan; (vi) our 2016 stock incentive plan, or 2016 Plan; and (vii) our 2016 manager incentive plan, or 2016 Manager Plan. We refer to our 1997 Plan, our 2007 Plan, our 2011 Plan, our 2013 Plan, and our 2013 Manager Plan, collectively, as our Expired Plans and we refer to our 2016 Plan and 2016 Manager Plan, collectively, as our Current Plans.

Our Expired Plans have expired and no new awards may be issued under them. Under our Current Plans, a maximum of 2,400,000 shares of our class A common stock may be issued to our Manager, our directors and officers, and certain employees of affiliates of our Manager. As of March 31, 2018, there were 488,153 shares available under the Current Plans.

The following table details the movement in our outstanding shares of restricted class A common stock and the weighted-average grant date fair value per share:


	Restricted Class A Common Stock			Weighted-Average Grant Date Fair Value Per Share
Balance as of December 31, 2017		1,484,175		$	30.61
Granted		318,741			31.83
Vested		(136,738	)		28.92
Forfeited		(8,966	)		30.54

Balance as of March 31, 2018		1,657,212		$	30.98

These shares generally vest in installments over a three-year period, pursuant to the terms of the respective award agreements and the terms of the Current Plans. The 1,657,212 shares of restricted class A common stock outstanding as of March 31, 2018 will vest as follows: 719,642 shares will vest in 2018; 620,323 shares will vest in 2019; and 317,247 shares will vest in 2020. As of March 31, 2018, total unrecognized compensation cost relating to nonvested share-based compensation arrangements was $42.0 million based on the closing price of our class A common stock of $31.42 on March 29, 2018, the last trading day in the quarter ended March 31, 2018. This cost is expected to be recognized over a weighted average period of 1.1 years from March 31, 2018.