The Company’s share-based compensation plans are intended to attract and retain employees and to provide an incentive for them to assist the Company to achieve long-range performance goals and to enable them to participate in long-term growth of the Company. The Company settles restricted stock unit awards and stock option exercises with newly issued common shares.

Onto Innovation Inc. 2020 Stock Plan (the “2020 Plan”). The 2020 Plan provides for the grant of 3,613 stock options and other stock awards to employees, directors and consultants at an exercise price equal to the fair market value of the common stock on the date of grant. Options granted under the 2020 Plan typically grade vest over a three-year period and expire ten years from the date of grant. Restricted stock units granted under the 2020 Plan typically vest over a three-year period for employees and one year for directors; however, other vesting periods are allowable under the 2020 Plan. Restricted stock units granted to employees have time based or performance based vesting. As of December 26, 2020, there were 3,555 shares of common stock available for issuance pursuant to future grants under the 2020 Plan.

	Year Ended December 26,			Year Ended December 31,
	2020			2019			2018
Share-based compensation expense:
Restricted stock units, including all performance and market based awards	$	15,780		$	10,421		$	6,062
Stock options and employee stock purchase options		1,882			164			—
Total share-based compensation		17,662			10,585			6,062
Tax effect on share-based compensation		3,849			2,283			1,362
Net effect on net income	$	13,813		$	8,302		$	4,700
Effect on earnings per share:
Basic	$	(0.28	)	$	(0.28	)	$	(0.18	)
Diluted	$	(0.28	)	$	(0.28	)	$	(0.18	)

A summary of the Company’s restricted stock unit activity with respect to the years ended December 26, 2020, December 31, 2019 and December 31, 2018 follows:

	Number of Shares			Weighted Average Grant Date Fair Value
Nonvested at December 31, 2017		816		$	18.50
Granted		228		$	34.80
Vested		(325	)	$	17.73
Forfeited		(80	)	$	22.12
Nonvested at December 31, 2018		639		$	24.26
Granted		271		$	29.58
Assumed in Merger		598		$	31.43
Vested		(366	)	$	25.69
Forfeited		(35	)	$	26.44
Nonvested at December 31, 2019		1,107		$	28.89
Granted		498		$	34.71
Vested		(498	)	$	29.46
Forfeited		(143	)	$	29.99
Nonvested at December 26, 2020		964		$	31.37

As of December 26, 2020, there was $19,135 of total unrecognized compensation cost related to restricted stock units granted under the plans. That cost is expected to be recognized over a weighted average period of 1.7 years.

A summary of the Company’s stock option activity with respect to the years ended December 26, 2020, December 31, 2019 and December 31, 2018 follows:

	Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2017		59		$	15.20
Granted		—			—
Exercised		(22	)		15.20
Expired		—			—
Forfeited		—			—
Outstanding at December 31, 2018		37			15.20
Granted		—			—
Assumed in Merger		12			16.27
Exercised		(2	)		14.96
Expired		—			—
Forfeited		—			—
Outstanding at December 31, 2019		47		$	15.49
Granted		—			—
Exercised		(19	)		15.84
Expired		—			—
Forfeited		—			—
Outstanding at December 26, 2020		28		$	15.25		1.9	$	915
Vested or expected to vest at December 26, 2020		28		$	15.25		1.9	$	915
Exercisable at December 26, 2020		28		$	15.25		1.9	$	915

The total intrinsic value of the stock options exercised during fiscal years 2020, 2019 and 2018 was $420, $51 and $384, respectively. As of December 26, 2020, there was no unrecognized compensation cost related to stock options granted under the plans.

The options outstanding and exercisable at December 26, 2020 were in the following exercise price ranges:

Onto Innovation Inc. 2020 Employee Stock Purchase Plan (the “2020 ESPP”). Under the terms of the 2020 ESPP, eligible employees may have up to 10% of eligible compensation deducted from their pay and applied to the purchase of shares of Company common stock. The price the employee pays for each share of stock is 85% of the lesser of the fair market value of Company common stock at the beginning or the end of the applicable six-month purchase period. The 2020 ESPP is intended to qualify under Section 423 of the Internal Revenue Code and is a compensatory plan as defined by FASB ASC 718, “Stock Compensation.”

Through the Company’s employee stock purchase plans, employees purchased 91, 72 and 13 shares during the twelve months ended December 26, 2020, December 31, 2019 and December 31, 2018, respectively. As of December 26, 2020 and December 31, 2019, there were 1,500 and 236, shares available for issuance under the Company’s employee stock purchase plans, respectively.

The Company has a 401(k) savings plan that allows employees to contribute up to 100% of their annual compensation to the Plan on a pre-tax or after-tax basis, limited to a maximum annual amount as set periodically by the Internal Revenue Service. The plan provides a 50% match of all employee contributions up to 6 percent of the employee’s salary. Matching contributions to the plan totaled $2,315, $1,317 and $1,118 for the years ended December 26, 2020, December 31, 2019 and December 31, 2018, respectively.