Information related to stock options under the Restated Employee Equity Incentive Plan and the Stock Option Plan for Non-Employee Directors is summarized as follows:

	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term in Years		Aggregate Intrinsic Value (in thousands)
Outstanding at December 26, 2020		241,847		$	228.58
Granted		18,998			1,028.71
Forfeited		-			-
Expired		-			-
Exercised		(31,020	)		195.05
Outstanding at March 27, 2021		229,825		$	229.25		3.30	$	120,540
Exercisable at March 27, 2021		81,710		$	214.22		3.30	$	197,820
Vested and expected to vest at March 27, 2021		210,570		$	294.96		3.30	$	182,149

Of the total options outstanding at March 27, 2021, 23,019 shares were performance-based options for which the performance criteria had yet to be achieved.

On March 1, 2021, the Company granted options to purchase an aggregate of 8,063 shares of the Company’s Class A Common Stock to senior management with a weighted average fair value of $449.93 per share, of which all shares relate to performance-based stock options.

On March 1, 2021 the Company granted options to purchase an aggregate of 10,935 shares of the Company’s Class A Common Stock to the Chief Executive Officer with a weighted average fair value of $457.25 per share, of which all shares relate to service-based stock options.

Weighted average assumptions used to estimate fair values of stock options on the date of grants are as follows:

The following table summarizes vesting activities of shares issued under the investment share program and restricted stock awards:

	Number of Shares			Weighted Average Fair Value
Non-vested at December 26, 2020		114,316		$	263.47
Granted		17,632			880.81
Vested		(22,885	)		221.81
Forfeited		(196	)		150.24
Non-vested at March 27, 2021		108,867		$	373.08

Of the total shares outstanding at March 27, 2021, 2,696 shares were performance-based shares for which the performance criteria had yet to be achieved.

On March 1, 2021, the Company granted a combined 7,817 shares of restricted stock units to certain officers, senior managers and key employees, of which all shares vest ratably over service periods of four years. Additionally on March 1, 2020, the Company granted 4,861 shares of restricted stock units to the Chief Executive Officer, of which all shares vest over five years. On March 1, 2021,

employees elected to purchase a combined 4,954 shares under the Company’s investment share program. The weighted average fair value of the restricted stock units and investment shares, which are sold to employees at discount under its investment share program, was $1,028.71 and $502.32 per share, respectively.

The following table provides information regarding stock-based compensation expense included in operating expenses in the accompanying consolidated statements of comprehensive income:

	Thirteen weeks ended
	March 27, 2021		March 28, 2020
	(in thousands)
Amounts included in advertising, promotional and selling expenses	$	1,672	$	705
Amounts included in general and administrative expenses		3,285		1,861
Total stock-based compensation expense	$	4,957	$	2,566