Note 18 — Quarterly financial data (unaudited)

	First		Second		Third		Fourth
2017:
Sales	$	407,470	$	496,137	$	589,438	$	573,938
Gross margin		225,138		275,512		326,265		312,088
Net income		49,988		64,523		101,456		79,835
Earnings per share:
Basic		0.87		1.12		1.76		1.38
Diluted		0.86		1.11		1.74		1.37
2016:
Sales	$	372,220	$	437,592	$	489,899	$	509,283
Gross margin		196,907		248,405		273,220		274,967
Net income		41,161		70,601		84,214		75,867
Earnings per share:
Basic		0.72		1.24		1.48		1.33
Diluted		0.72		1.23		1.46		1.31

The sum of the per-share amounts for the four quarters may not always equal the annual per-share amounts due to differences in the average number of shares outstanding during the respective periods. The sum of other amounts for the four quarters may not always equal the annual amounts due to rounding.

During the fourth quarter of 2017, we recorded pre-tax severance and restructuring costs of $1,017 and we recorded pre-tax acquisition costs of $391 related to the acquisition of Vention.

During the third quarter of 2017, we recorded pre-tax severance and restructuring costs of $703 and we recorded pre-tax acquisition costs of $865 related to Vention.

During the second quarter of 2017, we recorded pre-tax severance and restructuring costs of $491 and we recorded pre-tax acquisition costs of $13,415 related Vention. As a result, our income tax provision for the second quarter included a discrete tax expense of $2,600 related to nondeductible acquisition costs.

During the first quarter of 2017, we recorded pre-tax severance and restructuring costs of $227.

During the fourth quarter of 2016, we recorded pre-tax severance and restructuring costs of $6,411.

During the third quarter of 2016, we recorded pre-tax severance and restructuring costs of $1,714 and we recorded other expense of $2,722 related to the reversal of an indemnification asset resulting from the effective settlement of a tax exam. Additionally, our income tax provision for the third quarter included a discrete tax benefit of $1,651 related to the effective settlement of a tax exam.

During the second quarter of 2016, we recorded pre-tax severance and restructuring costs of $1,633. Additionally, we recorded other income of $800 related to a favorable litigation settlement and a $1,192 favorable adjustment to unrecognized tax benefits related to the effective settlement of a tax exam. Furthermore, our income tax provision for the second quarter included a discrete tax benefit of $1,136 related to the effective settlement of a tax exam.

During the first quarter of 2016, we recorded pre-tax severance and restructuring costs of $1,017.

On December 18, 2015, the Protecting Americans from Tax Hikes Act of 2015 was enacted which retroactively reinstated the Federal Research and Development Tax Credit (Federal R&D Tax Credit) as of January 1, 2015, and made it permanent. As a result, our income tax provision for the three months ended January 31, 2016 includes a discrete tax benefit of $2,025 primarily related to 2015. Additionally, our income tax provision for the first quarter included a discrete tax benefit of $6,184 related to dividends paid from previously taxed foreign earnings.