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(3)������Stock-Based Compensation

The Company has granted to certain of its directors, employees and employees of its subsidiaries, restricted stock, restricted stock units (“RSUs”) and options to purchase shares of the Company’s common stock (collectively, "Awards"). The Company measures the cost of employee services received in exchange for an equity classified Award (such as stock options and restricted stock) based on the grant-date fair value (“GDFV”) of the Award, and recognizes that cost over the period during which the employee is required to provide service (usually the vesting period of the Award). The Company measures the cost of employee services received in exchange for a liability classified Award based on the current fair value of the Award, and remeasures the fair value of the Award at each reporting date.

Included in selling, general and administrative expenses in the accompanying condensed consolidated statements of operations are $17 million and $21 million of stock-based compensation during the three months ended September��30, 2019 and 2018, respectively, and $54 million and $67 million of stock-based compensation during the nine months ended September��30, 2019 and 2018, respectively.

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The following table presents the number and weighted average GDFV of options granted by the Company during the nine months ended September��30, 2019:

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In addition to the stock option grant to the ���߲ݴ�ý Chairman of the Board and in connection with our Chairman’s employment agreement, during the nine months ended September 30, 2019, ���߲ݴ�ý granted 213 thousand RSUs of Series B ���߲ݴ�ý common stock of which 194 thousand were performance-based. The Series B RSUs had a GDFV of $17.90 per share at the time they were granted. ��The time-based RSUs cliff vested on March 11, 2019, and the performance-based RSUs cliff vest one year from the month of grant, subject to the satisfaction of certain performance objectives. ��During the nine months ended September 30, 2019, ���߲ݴ�ý also granted approximately 191 thousand performance-based RSUs of Series A ���߲ݴ�ý common stock to its CEO. ��The Series A RSUs had a GDFV of $17.90 per share at the time they were granted and will cliff vest one year from the month of grant, subject to satisfaction of certain performance objectives. Performance objectives, which are subjective, are considered in determining the timing and amount of compensation expense recognized. When the satisfaction of the performance objectives becomes probable, the Company records compensation expense. The probability of satisfying the performance objectives is assessed at the end of each reporting period.

The Company has calculated the GDFV for all of its equity classified Awards and any subsequent remeasurement of its liability classified Awards and certain performance-based Awards using the Black-Scholes-Merton Model. The Company estimates the expected term of the Awards based on historical exercise and forfeiture data. The volatility used in the calculation for Awards is based on the historical volatility of ���߲ݴ�ý's stock and the implied volatility of publicly traded ���߲ݴ�ý options. The Company uses a zero dividend rate and the risk-free rate for Treasury Bonds with a term similar to that of the subject options.

���߲ݴ�ý—Outstanding Awards

The following tables present the number and weighted average exercise price ("WAEP") of the Awards to purchase ���߲ݴ�ý common stock granted to certain officers, employees and directors of the Company, as well as the weighted average remaining life and aggregate intrinsic value of the Awards.

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As of September��30, 2019, the total unrecognized compensation cost related to unvested Awards was approximately $46 million. Such amount will be recognized in the Company's consolidated statements of operations over a weighted average period of approximately 2.3 years.

As of September��30, 2019, ���߲ݴ�ý reserved for issuance upon exercise of outstanding stock options approximately 27.7 million shares of Series A ���߲ݴ�ý common stock and 1.8 million shares of Series B ���߲ݴ�ý common stock.