On May 16, 2018, our shareholders approved our 2018 Stock Option and Stock Incentive Plan (the “2018 Plan” or the “Plan”), which supersedes our 2008 Stock Option and Stock Incentive Plan. Under the terms of the Plan, our Board of Directors may grant up to 1,200,000 shares of common stock in the form of shares of restricted stock, restricted stock units, stock appreciation rights, stock options, or combinations thereof, to officers, directors, employees, consultants and advisors. Grants under the Plan must be made within ten years of the date the Plan was approved. Stock options are exercisable upon the terms set forth in each grant agreement, but in no event more than ten years from the date of grant. Restricted stock and restricted stock units vest in accordance with the terms set forth in each applicable award agreement. At September 28, 2019, 1,035,216 shares were available for grant under the 2018 Plan.

We may grant restricted stock to officers, directors, employees, consultants and advisors. Vesting of restricted stock is conditional based on continued employment or service for a specified period and, in certain circumstances, the attainment of performance goals. We retain the unvested restricted stock, and any dividends paid thereon, until the vesting conditions have been met. For time-based restricted stock awards, compensation cost related to the stock is recognized on a straight-line basis over the vesting period and is calculated using the closing price per share of our common stock on the grant date. For performance-based restricted stock awards tied to growth in adjusted pre-tax income, compensation cost related to the stock is recognized over the performance period and is calculated using the closing price per share of our common stock on the grant date and an estimate of the probable outcome of the performance conditions as each the reporting date. In 2019, we introduced performance-based shares that vest based on our total shareholder return ranking relative to the S&P Midcap 400 Growth Index over a three-year performance period. For performance-based restricted stock awards tied to total shareholder return, compensation cost related to the stock is recognized on a straight-line basis over the performance period and is calculated using the simulated fair value per share of our common stock based on the application of a Monte Carlo simulation model. Compensation cost related to restricted stock was $2.3 million and $2.5 million for the thirty-nine weeks ended September 28, 2019 and September 29, 2018, respectively, and is classified as selling, general and administrative expense in the Consolidated Statements of Operations.

The following table summarizes our restricted stock activity for the thirty-nine weeks ended September 28, 2019:

	Shares			Weighted Average Price
Balance at December 29, 2018		170,737		$	63.94
Granted		90,434		$	82.10
Vested		(38,764	)	$	55.00
Cancelled		(33,504	)	$	52.08
Balance at September 28, 2019		188,903		$	76.57

As of September 28, 2019, there was $7.5 million of unrecognized compensation cost related to unvested restricted stock, which is expected to be recognized over a weighted-average period of approximately 2.6 years.

Cash flows resulting from tax deductions in excess of the tax effect of compensation cost recognized in the financial statements are classified as operating cash flows. The excess tax benefit generated from restricted stock which vested was $0.2 million and less than $0.1 million in the thirty-nine weeks ended September 28, 2019 and September 29, 2018, respectively, and was credited to income tax expense.

We may grant stock options to officers, directors, employees, consultants and advisors. We expense the grant-date fair value of stock options. Compensation cost is recognized on a straight-line basis over the vesting period for which related services are performed. The compensation cost charged against income was $0.5 million and $0.4 million for the thirty-nine weeks ended September 28, 2019 and September 29, 2018, respectively. The compensation costs were classified as selling, general and administrative expense in the Consolidated Statements of Operations. No cost was capitalized during the thirty-nine weeks ended September 28, 2019 and September 29, 2018.

We use the Black-Scholes option valuation model to estimate the fair value of stock options granted. Expected volatility and expected dividend yield are based on the actual historical experience of our common stock. The expected life represents the period of time that options granted are expected to be outstanding and was calculated using historical option exercise data. The risk-free rate was based on a U.S. Treasury security with terms equal to the expected time of exercise as of the grant date. During the thirty-nine weeks ended September 28, 2019 and September 29, 2018, we granted 38,670 and 69,014 stock options, respectively.

The following table summarizes our stock option activity for the thirty-nine weeks ended September 28, 2019:

	Shares			Weighted Average Exercise Price		Weighted Average Remaining Term (In years)		Aggregate Intrinsic Value
Balance at December 29, 2018		188,469		$	66.14
Granted		38,670		$	82.94
Exercised		(35,401	)	$	59.90
Forfeited		(2,597	)	$	76.03
Balance at September 28, 2019		189,141		$	70.61		3.9	$	1,815,121
Options exercisable at September 28, 2019		65,972		$	61.51		2.4	$	1,165,216

There were 35,401 and 4,000 options exercised during the thirty-nine weeks ended September 28, 2019 and September 29, 2018, respectively. As of September 28, 2019, there was $1.8 million of unrecognized compensation cost related to non-vested stock options, which is expected to be recognized over a weighted-average period of 2.8 years.

Cash generated from stock option exercises was less than $0.1 million in the thirty-nine weeks ended September 28, 2019. There was no cash received from stock option exercises in the thirty-nine weeks ended September 29, 2018.

There was no excess tax benefit generated from stock options exercised in the thirty-nine weeks ended September 28, 2019 or September 29, 2018.

In May 2017, our shareholders’ approved the Dorman Products, Inc. Employee Stock Purchase Plan (the “ESPP”), which made available up to 1,000,000 shares of our common stock for sale to eligible employees. There were 13,669 and 7,382 shares purchased under this plan in the thirty-nine weeks ended September 28, 2019 and September 29, 2018, respectively. During the thirty-nine weeks ended September 28, 2019 and September 29, 2018, compensation cost under the ESPP was $0.2 million.