STOCK-BASED AWARDS

We have equity incentive plans that provide for the grant to employees and board members of stock-based awards, including stock options and restricted stock. Stock-based compensation expense was as follows (in thousands):



	Three months ended March 31,
	2018		2017
Overstock restricted stock awards	$	2,384	$	940
Medici Ventures stock options	11		—
tZERO equity awards	4,040		—
Total stock-based compensation expense	$	6,435	$	940

Overstock restricted stock awards

During the three months ended March 31, 2018, the Compensation Committee of the Board of Directors approved grants of 322,092 restricted stock awards to our officers, board members and employees. The restricted stock awards generally vest over three years at 33.3% at the end of the first year, 33.3% at the end of the second year and 33.3% at the end of the third year and are subject to the recipient's continuing service to us. At March 31, 2018, 688,830 unvested restricted stock awards remained outstanding.

The cost of restricted stock awards is determined using the fair value of our common stock on the date of the grant, and compensation expense is either recognized on a straight-line basis over the three-year vesting schedule or on an accelerated schedule when vesting of restricted stock awards exceeds a straight-line basis. The cumulative amount of compensation expense recognized at any point in time is at least equal to the portion of the grant date fair value of the award that is vested at that date. The weighted average grant date fair value of restricted stock awards granted during the three months ended March 31, 2018 was $73.22.

The following table summarizes restricted stock award activity during the three months ended March 31, 2018 (in thousands):



	Three months ended March 31, 2018
	Units		Weighted Average Grant Date Fair Value
Outstanding—beginning of year	540		$	17.05
Granted at fair value	322		73.22
Vested	(166	)	15.55
Forfeited	(7	)	52.75
Outstanding—end of period	689		$	43.35

Medici Ventures stock options

In July 2017, the Board of Directors of Medici Ventures approved the Medici Ventures, Inc. 2017 Stock Option Plan, which provides for the grant of options to employees and directors of and consultants to Medici Ventures to acquire up to a total of 10% of the authorized shares of Medici Ventures' common stock. Pursuant to the plan, the Board of Directors approved grants of 74,750 stock options to certain Medici Ventures and Overstock employees during the year ended December 31, 2017. The stock options were valued in total at $91,000 and subject to two vesting schedules, and compensation expense is recognized on a straight-line basis over the vesting schedules.

tZERO equity awards

In December 2017, the Board of Directors of tZERO approved the tZERO.com 2017 Equity Incentive Plan pursuant to which it may grant compensatory options to acquire up to 5% of tZERO’s common stock. In January 2018, tZERO granted stock awards under the equity incentive plan for an aggregate of approximately 1.0% of tZERO’s common stock all of which vested on January 23, 2018. In January 2018, tZERO recognized $4.0 million in compensation expense associated with these awards, which was the entire estimated fair value at the grant date. Accordingly, there is no expense to be recognized in future periods related to these awards. As a result of these vested awards, our indirect ownership interest in tZERO was reduced from 81% to approximately 80%.