6. Stock-Based Compensation

The Company accounts for stock-based compensation in accordance with ASC 718, Compensation- Stock Compensation, which requires measurement of compensation cost for all stock awards at fair value on the date of grant and recognition of compensation, net of forfeitures, over the requisite service period for awards expected to vest. Stock compensation expense for the thirteen weeks ended March 26, 2020 and March 28, 2019 was $2.9 million and $2.2 million, respectively, and was included in general and administrative expenses on the Company’s condensed consolidated statement of operations and comprehensive income.

On February 24, 2020, the Company granted a combination of stock options, restricted stock units, and restricted stock to our non-employee directors and certain of our employees under the 2017 Stock Incentive Plan as part of our annual long-term incentive grants, as outlined below.

Stock Options

The stock options granted to eligible employees during the first quarter of fiscal 2020 had a weighted average grant-date fair value of $21.81 and vest in four ratable annual installments on each of the first four anniversaries of the grant date, subject to the grantee’s continued service through the applicable vesting date. The Company estimates the fair value of stock option grants using the Black-Scholes-Merton option pricing model with the following weighted average assumptions:

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The Company determines the grant date fair value of stock options with assistance from a third-party valuation specialist. Expected volatility is estimated based on the historical volatility of the Company’s Class A common stock since its initial public offering in 2017 as well as the historical volatility of the common stock of similar public entities. The Company considers various factors in determining the appropriateness of the public entities used in determining expected volatility, including the entity's life cycle stage, industry, growth profile, size, financial leverage, and products offered. To determine the expected life of the options granted, the Company relied upon a combination of the observed exercise behavior of prior grants with similar characteristics and the contractual terms and vesting schedules of the current grants. The risk-free interest rate is based on the term structure of interest rates at the time of the option grant.

Stock option activity during the thirteen weeks ended March 26, 2020 was as follows: 

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The Company’s total unrecognized compensation cost related to stock options as of March 26, 2020 was $22,753 thousand, which is expected to be recognized over a weighted average period of 2.8 years.

Restricted Stock Units

During the thirteen weeks ended March 26, 2020, the Company granted 108,242 restricted stock units to certain employees with a weighted average grant-date fair value of $57.70. The restricted stock units granted to eligible employees represent an unfunded, unsecured right to receive a share of the Company’s Class A common stock upon vesting. These awards vest in four ratable annual installments on each of the first four anniversaries of the grant date, subject to the grantee’s continued service through the applicable vesting date. The fair value of the restricted stock units was determined based on the closing price of the Company’s Class A common stock on the date of grant.

The Company’s total unrecognized compensation cost related to restricted stock units as of March 26, 2020 was $6,096 thousand, which is expected to be recognized over a weighted average period of 3.9 years.

Restricted Stock Awards

During the thirteen weeks ended March 26, 2020, the Company issued 367,702 shares of restricted stock to certain executive officers and non-employee directors, comprised of 160,315 shares of restricted stock with a payout subject to certain performance criteria (“performance-based restricted stock”), 104,456 shares of restricted stock with a payout subject to the Company’s total shareholder return (“TSR”) compared to a specified peer group (“TSR awards”), and 102,931 shares of restricted stock that vest based on the grantee’s continued service through the applicable vesting dates (“service-based restricted stock”).

The fair value of performance-based and service-based restricted stock awards is based on the closing market price of the Company's Class A common stock on the date of grant. The fair value of the TSR awards is estimated on grant date using the Monte Carlo valuation method. The weighted-average fair value of all restricted stock granted during the first quarter of fiscal 2020 was $53.89.

Compensation cost for restricted stock awards is recognized using the straight-line method over the requisite service period, which for each of the awards is the service vesting period. The service vesting period for awards granted during the first quarter of fiscal 2020 was one year for non-employee directors and ranged between three to four years for awards to executive officers. As of March 26, 2020, total unrecognized compensation cost related to unvested restricted stock awards was $20,085 thousand, which is expected to be recognized over a weighted average period of 3.8 years.

The performance-based restricted stock cliff vest based on (i) the Company's achievement of pre-determined financial metrics at the end of a three-year performance period and (ii) the grantee’s continued service through the vesting date. The TSR awards cliff vest based on (i) the Company's relative total shareholder return (“TSR”) compared to a specified peer group, with no vesting unless the Company’s TSR exceeds the median TSR of the specified peer group and (ii) the grantee’s continue service through the vesting date. In accordance with ASC 718, Stock Compensation, as the TSR awards are subject to a market condition, their fair value was estimated using a Monte Carlo valuation model with the following assumptions:

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