We recognized share-based payment expense of $23,393 and $21,805 for the three months ended September 30, 2015 and 2014, respectively, and $62,334 and $57,832 for the nine months ended September 30, 2015 and 2014, respectively.

2015 Long-Term Stock Incentive Plan

In May 2015, our stockholders approved the Sirius XM Holdings Inc. 2015 Long-Term Stock Incentive Plan (the “2015 Plan”).  Employees, consultants and members of our board of directors are eligible to receive awards under the 2015 Plan.  The 2015 Plan provides for the grant of stock options, restricted stock awards, restricted stock units and other stock-based awards that the compensation committee of our board of directors deem appropriate.  Vesting and other terms of stock-based awards are set forth in the agreements with the individuals receiving the awards.  Stock-based awards granted under the 2015 Plan are generally subject to a vesting requirement.  Stock options generally expire ten years from the date of grant.  Each restricted stock unit entitles the holder to receive one share of common stock upon vesting.  As of September 30, 2015, 292,790 shares of common stock were available for future grants under the 2015 Plan.

Other Plans

We maintain four other share-based benefit plans — the Sirius XM Radio Inc. 2009 Long-Term Stock Incentive Plan, the XM 2007 Stock Incentive Plan, the Amended and Restated Sirius Satellite Radio 2003 Long-Term Stock Incentive Plan and the XM 1998 Shares Award Plan. No further awards may be made under these plans.  

The following table summarizes the weighted-average assumptions used to compute the fair value of options granted to employees and members of our board of directors:

There were no options granted to third parties during the three and nine months ended September 30, 2015 and 2014.  We do not intend to pay regular dividends on our common stock.  Accordingly, the dividend yield percentage used in the Black-Scholes-Merton option value was zero for all periods.

The following table summarizes stock option activity under our share-based plans for the nine months ended September 30, 2015:

The weighted average grant date fair value per share of options granted during the nine months ended September 30, 2015 and 2014 was $0.91 and $1.05, respectively.  The total intrinsic value of stock options exercised during the nine months ended September 30, 2015 and 2014 was $85,387 and $62,650, respectively.  During the nine months ended September 30, 2015, the number of shares which were issued as a result of stock option exercises was 12,761.

We recognized share-based payment expense associated with stock options of $19,418 and $19,318 for the three months ended September 30, 2015 and 2014, respectively, and $52,662 and $52,126 for the nine months ended September 30, 2015 and 2014, respectively.

The following table summarizes the restricted stock unit and stock award activity under our share-based plans for the nine months ended September 30, 2015:

The weighted average grant date fair value per share of restricted stock units and stock awards granted during the nine months ended September 30, 2015 and 2014 was $3.91 and $3.39, respectively.  The total intrinsic value of restricted stock units and stock awards vesting during the nine months ended September 30, 2015 and 2014 was $9,565 and $3,924, respectively.  During the nine months ended September 30, 2015, the number of shares which were issued as a result of restricted stock units and stock awards vesting was 1,595.

We recognized share-based payment expense associated with restricted stock units and stock awards of $3,975 and $2,487 during the three months ended September 30, 2015 and 2014, respectively, and $9,672 and $5,706 during the nine months ended September 30, 2015 and 2014, respectively.

Total unrecognized compensation costs related to unvested share-based payment awards for stock options and restricted stock units granted to employees and members of our board of directors at September 30, 2015 and December 31, 2014, net of estimated forfeitures, were $215,895 and $162,985, respectively.  The total unrecognized compensation costs at September 30, 2015 are expected to be recognized over a weighted-average period of 3 years.

401(k) Savings Plan

Sirius XM sponsors the Sirius XM Radio Inc. 401(k) Savings Plan (the “Sirius XM Plan”) for eligible employees. The Sirius XM Plan allows eligible employees to voluntarily contribute from 1% to 50% of their pre-tax eligible earnings, subject to certain defined limits. We match 50% of an employee’s voluntary contributions per pay period on the first 6% of an employee’s pre-tax salary up to a maximum of 3% of eligible compensation.  Employer matching contributions under the Sirius XM Plan vest at a rate of 33.33% for each year of employment and are fully vested after three years of employment for all current and future contributions.  Beginning in January 2014, our cash employer matching contributions were no longer used to purchase shares of our common stock on the open market, unless the employee elects our common stock as their investment option for this contribution.  We contributed $1,486 and $1,190 during three months ended September 30, 2015 and 2014, respectively, and $6,026 and $4,323 during the nine months ended September 30, 2015 and 2014, respectively, to the Sirius XM Plan in fulfillment of our matching obligation.

Sirius XM Holdings Inc. Deferred Compensation Plan

In June 2015, we adopted the Sirius XM Holdings Inc. Deferred Compensation Plan (the “DCP”), effective July 1, 2015.  The DCP allows members of our Board of Directors and certain eligible employees to defer all or a portion of their base salary, cash incentive compensation and/or Board of Directors compensation, as applicable, each plan year.  Pursuant to the terms of the DCP, we may elect to make additional contributions beyond amounts deferred by participants, but we are under no obligation to do so.  We intend to establish a grantor (or “rabbi”) trust to facilitate the payment of our obligations under the DCP.  As of September 30, 2015, there were no balances or amounts associated with the DCP that were recorded in our unaudited consolidated financial statements.