Goodwill represents the excess of the purchase price over the estimated fair value of the net tangible and identifiable intangible assets acquired in business combinations.  Our annual impairment assessment of our single reporting unit is performed as of the fourth quarter of each year, and an assessment is performed at other times if an event occurs or circumstances change that would more likely than not reduce the fair value of the asset below its carrying value.  Step one of the impairment assessment compares the fair value to its carrying value and if the fair value exceeds its carrying value, goodwill is not impaired.  If the carrying value exceeds the fair value, the implied fair value of goodwill is compared to the carrying value of goodwill.  If the implied fair value exceeds the carrying value then goodwill is not impaired; otherwise, an impairment loss will be recorded by the amount the carrying value exceeds the implied fair value.  At the date of our annual assessment for 2015 and 2014, the fair value of our single reporting unit substantially exceeded its carrying value and therefore was not at risk of failing step one of ASC 350-20, Goodwill. ASC 350-35 states that if the carrying amount of the reporting unit is zero or negative, the second step of the impairment test shall be performed to measure the amount of impairment loss, if any, when it is more likely than not that a goodwill impairment exists based on adverse qualitative factors.  Subsequent to our annual assessment performed in the fourth quarter of 2015, we were not aware of any adverse qualitative factors that would indicate any impairment to our goodwill as of December 31, 2015.

No impairment losses were recorded for goodwill during the years ended December 31, 2015, 2014 and 2013.  As of December 31, 2015, the cumulative balance of goodwill impairments recorded since the July 2008 merger (the "Merger") between our wholly owned subsidiary, Vernon Merger Corporation, and XM Satellite Radio Holdings Inc. ("XM"), was $4,766,190, which was recognized during the year ended December 31, 2008.