STOCKHOLDERS' EQUITY AND COMPENSATION ARRANGEMENTS

The Company's Board of Directors (the "Board") has the authority, without approval by the stockholders, to issue up to a total of 50,000,000 shares of preferred stock in one or more series. The Board may establish the number of shares to be included in each such series and may fix the designations, preferences, powers and other rights of the shares of a series of preferred stock. The Board could authorize the issuance of preferred stock with voting or conversion rights that could dilute the voting power or rights of the holders of its common stock. As of March 31, 2018 and December 31, 2017, there were no shares of preferred stock outstanding.

Common Stock

Pursuant to the Company's restated certificate of incorporation, the Board has the authority to issue up to a total of 2,010,000,000 shares of common stock. Each holder of common stock shall be entitled to one vote for each such share on any matter that is submitted to a vote of stockholders. In addition, holders of the common stock will vote as a single class of stock on any matter that is submitted to a vote of stockholders.

Share Repurchase Program

In May 2018, the Board authorized the Company to repurchase up to $300.0 million of its common stock under a new share repurchase program. The Company's prior share repurchase program expired in April 2018. During the three months ended March 31, 2018, the Company did not purchase any shares under that program. As of March 31, 2018 and upon its expiration the following month, up to $135.2 million of common stock remained available for purchase under that prior share repurchase program. The timing and amount of share repurchases, if any, will be determined based on market conditions, limitations under the Amended and Restated Credit Agreement, share price and other factors, and the share repurchase program may be terminated at any time.

Groupon, Inc. Stock Plans

The Groupon, Inc. Stock Plans (the "Plans") are administered by the Compensation Committee of the Board (the "Compensation Committee"), which determines the number of awards to be issued, the corresponding vesting schedule and the exercise price for options. As of March 31, 2018, 63,923,154 shares of common stock were available for future issuance under the Plans.

The stock-based compensation expense related to stock awards issued under the Plans and acquisition-related awards are presented within the following line items of the condensed consolidated statements of operations for the three months ended March 31, 2018 and 2017 (in thousands):



	Three Months Ended March 31,
	2018		2017
Cost of revenue	$	396	$	663
Marketing	1,794		1,802
Selling, general and administrative	17,088		17,185
Other income (expense)	48		51
Total stock-based compensation expense	$	19,326	$	19,701

The Company also capitalized $1.7 million and $1.5 million of stock-based compensation for the three months ended March 31, 2018 and 2017, respectively, in connection with internally-developed software. As of March 31, 2018, a total of $107.9 million of unrecognized compensation costs related to unvested employee stock awards are expected to be recognized over a remaining weighted-average period of 1.32 years.

Employee Stock Purchase Plan

The Company is authorized to grant up to 10,000,000 shares of common stock under its employee stock purchase plan ("ESPP"). For the three months ended March 31, 2018 and 2017, 746,773 and 877,845 shares of common stock, respectively, were issued under the ESPP.

Restricted Stock Units

The restricted stock units granted under the Plans generally have vesting periods between one and four years. Restricted stock units are amortized on a straight-line basis over the requisite service period.

The table below summarizes activity regarding unvested restricted stock units granted under the Plans for the three months ended March 31, 2018:



	Restricted Stock Units		Weighted-Average Grant Date Fair Value (per unit)
Unvested at December 31, 2017	28,939,110		$	4.32
Granted	2,610,912		5.24
Vested	(3,878,827	)	4.53
Forfeited	(1,608,149	)	4.02
Unvested at March 31, 2018	26,063,046		4.40

Performance Share Units

The performance share units granted under the Plans vest in shares of the Company's common stock upon the achievement of financial and operational targets specified in the respective award. The awards are subject to both continued employment through the performance period dictated by the award and certification by the Compensation Committee that the specified financial and operational targets have been achieved.

During the three months ended March 31, 2018, the Company granted performance share units for which the maximum number of common shares issuable upon vesting of those performance share units is 3,283,114 shares, the grant date fair value was $5.20 per unit and the total grant date fair value of the shares for which the performance conditions are expected to be met was $8.5 million. During the three months ended March 31, 2018, 278,635 shares of the Company's common stock were issued related to performance share units granted in the previous year following the Compensation Committee's certification of the Company's financial and operational metrics for the year ended December 31, 2017. The weighted average grant date fair value of those units was $3.78 per share.

Performance Bonus Awards

If bonus amounts earned under the Company's primary employee bonus plans exceed targeted bonus amounts because specified financial metrics of the Company exceed the performance conditions set forth in those plans, such excess is required to be settled in the Company's common stock. The Company's obligation to issue shares for employee bonus amounts exceeding the specified bonus targets is accounted for separately as a liability-classified stock-based compensation arrangement with performance conditions.

During the three months ended March 31, 2018, 1,240,379 shares of the Company's common stock were issued related to performance bonus awards granted in the previous year following the Compensation Committee's certification of the Company's financial and operational metrics for the year ended December 31, 2017. The weighted average grant date fair value of those awards was $5.20 per share.

Stock Options

The exercise price of stock options granted is equal to the fair value of the underlying stock on the date of grant. The contractual term for stock options expires ten years from the grant date. Stock options generally vested over a three or four-year period, with 25% of the awards vesting after one year and the remainder of the awards vesting on a monthly or quarterly basis thereafter.

The table below summarizes the stock option activity for the three months ended March 31, 2018:



	Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands) ⁽¹⁾
Outstanding and exercisable at December 31, 2017	885,580		$	0.62	1.76	$	3,967
Exercised	(2,400	)	2.36
Forfeited	—		—
Outstanding and exercisable at March 31, 2018	883,180		0.61		1.51	$	3,294

(1)

The aggregate intrinsic value of options outstanding and exercisable represents the total pretax intrinsic value (the difference between the fair value of the Company's stock on the last day of each period and the exercise price, multiplied by the number of options where the fair value exceeds the exercise price) that would have been received by the option holders had all option holders exercised their options as of March 31, 2018 and December 31, 2017, respectively.