Prior to November 1, 2013, Ceridian employees participated in a share-based compensation plan of the former ultimate parent of Ceridian, the 2007 Stock Incentive Plan (“2007 SIP”). Effective November 1, 2013, although most participants who held stock options under the 2007 SIP converted their options to a newly created option plan, the 2013 Ceridian HCM Holding Inc. Stock Incentive Plan, as amended (“2013 SIP”), a small number of participants maintained their stock options in the 2007 SIP. Concurrent with the IPO and legal reorganization, all outstanding stock options under the 2007 SIP were converted into options to purchase common stock of Ceridian. As of March 31, 2019, there were 2,500 stock options outstanding under the 2007 SIP.

Stock options awarded under the 2013 SIP vest either annually on a pro rata basis over a four- or five-year period or on a specific date if certain performance criteria are satisfied and certain equity values are attained. In addition, upon termination of service, all vested options must be exercised generally within 90 days after termination, or these awards will be forfeited. The stock option awards have a 10-year contractual term and have an exercise price that is not less than the fair market value of the underlying stock on the date of grant. As of March 31, 2019, there were 8,104,518 stock options and restricted stock units outstanding under the 2013 SIP. We do not intend to grant any additional awards under the 2007 SIP or the 2013 SIP.

On April 24, 2018, in connection with the IPO, the Board of Directors approved the Ceridian HCM Holding Inc. 2018 Equity Incentive Plan (“2018 EIP”), which authorizes the issuance of up to 13,500,000 shares of common stock to eligible participants through equity awards. (the “Share Reserve”). The Share Reserve may be increased on March 31 of each of the first ten calendar years during the term of the 2018 EIP, by the lesser of (i) three percent of the number of shares of our common stock outstanding on each January 31 immediately prior to the data of increase or (ii) such number of shares of our common stock determined by the Board of Directors. On March 31, 2019, the Share Reserve was increased by three percent of the number of shares of common stock outstanding on January 31, 2019, or 4,196,193 shares.

Equity awards under the 2018 EIP vest annually on a pro rata basis, generally over a four-year period. In addition, upon termination of service, all vested awards must be exercised within 90 days after termination, or these awards will be forfeited. The equity awards have a 10-year contractual term and have an exercise price that is not less than the fair market value of the underlying stock on the date of the grant. As of March 31, 2019, there were 9,359,755 stock options and restricted stock units outstanding and 8,336,438 shares available for future grants of equity awards under the 2018 EIP.

On November 9, 2018, the Compensation Committee of the Board of Directors approved the Ceridian HCM Holding Inc. Global Employee Stock Purchase Plan (the “GESPP”), which authorizes the issuance of up to 2,500,000 shares of common stock to eligible participants through purchases via payroll deductions at a discount to the fair market value of our common stock. The GESPP has a 10-year contractual term, and purchases will commence in the second quarter of 2019, subject to approval by the Company’s stockholders at our May 1, 2019 annual meeting of stockholders.

Total share-based compensation expense was $6.0 and $2.7 for three months ended March 31, 2019, and 2018, respectively.

Performance-based option activity under the 2007 SIP and the 2013 SIP for the period was as follows:

	Shares			Weighted Average Exercise Price (per share)			Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in millions)
Performance-based options outstanding at December 31, 2018		366,377		$	13.50			3.1	$	7.7
Granted		—			—			—		—
Exercised		(43,849	)		(13.64	)		—		—
Forfeited or expired		—			—			—		—
Performance-based options outstanding at March 31, 2019		322,528		$	13.48			2.9	$	12.2
Performance-based options exercisable at March 31, 2019		322,528		$	13.48			2.9	$	12.2

The performance criteria for all outstanding performance-based stock options was met on June 7, 2018, resulting in the vesting of all outstanding performance-based stock options on this date. As of March 31, 2019, there was no share-based compensation expense related to unvested performance-based stock options not yet recognized.

Term-based option activity, including stock options under the 2007 SIP, the 2013 SIP and the 2018 EIP, for the period was as follows:

	Shares			Weighted Average Exercise Price (per share)			Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in millions)
Term-based options outstanding at December 31, 2018		13,549,769		$	19.28			7.5	$	206.8
Granted		4,112,295			49.66			—		—
Exercised		(1,186,362	)		(16.69	)		—		—
Forfeited or expired		(45,530	)		(21.22	)		—		—
Term-based options outstanding at March 31, 2019		16,430,172		$	26.83			8.1	$	402.1
Term-based options exercisable at March 31, 2019		4,960,532		$	16.84			5.6	$	170.9

As of March 31, 2019, there was $107.7 of share-based compensation expense related to unvested term based awards not yet recognized, which is expected to be recognized over a weighted average period of 2.3 years.

Restricted stock units (“RSUs”) activity, including RSUs under the 2013 SIP and the 2018 EIP, for the period was as follows:

	Shares
RSUs outstanding at December 31, 2018		664,073
Granted		50,000
Shares issued upon vesting of RSUs		—
Forfeited or canceled		—
RSUs outstanding at March 31, 2019		714,073
RSUs releasable at March 31, 2019		250,000

During the three months ended March 31, 2019, 125,000 RSUs vested. As of March 31, 2019, there were 464,073 unvested RSUs outstanding and 250,000 vested RSUs outstanding. RSUs generally vest annually over a three- or four-year period. As of March 31, 2019, there was $11.2 of share-based compensation expense related to unvested RSUs not yet recognized, which is expected to be recognized over a weighted average period of 2.4 years.