| RECONCILIATION OF GROSS MARGIN TO NON-GAAP GROSS MARGIN | ||||||||||||||||
| (Unaudited, in thousands) | ||||||||||||||||
|
Three Months Ended
December 31, |
Year Ended
December 31, | |||||||||||||||
| 2019 | 2018 | 2019 | 2018 | |||||||||||||
| Gross profit | $ | 91,936 | $ | 84,593 | $ | 346,325 | $ | 322,668 | ||||||||
| Gross margin | 55.1 | % | 55.1 | % | 55.2 | % | 55.4 | % | ||||||||
| Adjustments to reconcile gross profit to non-GAAP gross profit: | ||||||||||||||||
| Stock-based compensation expense | 574 | 504 | 2,409 | 1,888 | ||||||||||||
| Deferred compensation plan expense | 29 | - | 54 | - | ||||||||||||
| Amortization of acquisition-related intangible assets | - | 197 | 110 | 841 | ||||||||||||
| Non-GAAP gross profit | $ | 92,539 | $ | 85,294 | $ | 348,898 | $ | 325,397 | ||||||||
| Non-GAAP gross margin | 55.5 | % | 55.6 | % | 55.6 | % | 55.9 | % | ||||||||
