The following is a summary of the unaudited quarterly results of operations for the years ended December 31, 2016 and 2015 (in thousands, except per share amounts).

	2016
	March 31,			June 30,			September 30,			December 31,
Revenue	$	224,238		$	197,015		$	199,794		$	178,785
Operating expenses		178,117			173,996			174,069			171,544
Gross margin		46,121			23,019			25,725			7,241
Corporate general and administrative expenses		10,245			8,346			8,679			9,049
Operating income (loss)		35,876			14,673			17,046			(1,808	)
Other income (expense):
Interest expense		(1,526	)		(1,733	)		(1,760	)		(1,574	)
Gain on sale of operations, net		101			50			329			375
Other income, net		2,147			703			2,632			1,475
Total other income (expense), net		722			(980	)		1,201			276
Income (loss) from continuing operations before income tax expense (benefit)		36,598			13,693			18,247			(1,532	)
Income tax expense (benefit)		14,800			5,306			7,260			(967	)
Income (loss) from continuing operations		21,798			8,387			10,987			(565	)
Loss from operations of discontinued operations, net of tax		(30	)		(258	)		(133	)		(121	)
Net income (loss)	$	21,768		$	8,129		$	10,854		$	(686	)
Earnings (loss) per share:
Basic:
Continuing operations	$	0.42		$	0.16		$	0.21		$	(0.01	)
Discontinued operations		—			—			—			—
Net income (loss)	$	0.42		$	0.16		$	0.21		$	(0.01	)
Diluted:
Continuing operations	$	0.41		$	0.16		$	0.20		$	(0.01	)
Discontinued operations		—			—			—			—
Net income (loss)	$	0.41		$	0.16		$	0.20		$	(0.01	)
Basic weighted average common shares		51,572			52,031			52,648			53,019
Diluted weighted average common shares		52,745			53,079			53,846			53,019

	2015
	March 31,			June 30,			September 30,			December 31,
Revenue	$	213,866		$	185,042		$	187,102		$	164,412
Operating expenses (1)		170,864			163,117			158,496			159,914
Gross margin		43,002			21,925			28,606			4,498
Corporate general and administrative expenses (1)		9,865			6,615			8,028			8,019
Operating income (loss)		33,137			15,310			20,578			(3,521	)
Other (expense) income:
Interest expense		(2,977	)		(2,848	)		(1,840	)		(1,237	)
Gain (loss) on sale of operations, net		56			45			5			(22	)
Other income (loss), net (1)		2,859			(1,126	)		(2,367	)		1,780
Total other (expense) income, net		(62	)		(3,929	)		(4,202	)		521
Income (loss) from continuing operations before income tax expense (benefit)		33,075			11,381			16,376			(3,000	)
Income tax expense (benefit)		13,572			4,696			6,787			(2,226	)
Income (loss) from continuing operations		19,503			6,685			9,589			(774	)
Loss from operations of discontinued operations, net of tax		(335	)		(330	)		(561	)		(1,097	)
Gain (loss) on disposal of discontinued operations, net of tax		—			290			1,172			(35	)
Net income (loss)	$	19,168		$	6,645		$	10,200		$	(1,906	)
Earnings (loss) per share:
Basic:
Continuing operations	$	0.41		$	0.14		$	0.19		$	(0.02	)
Discontinued operations		(0.01	)		(0.01	)		0.01			(0.01	)
Net income (loss)	$	0.40		$	0.13		$	0.20		$	(0.03	)
Diluted:
Continuing operations	$	0.38		$	0.13		$	0.18		$	(0.02	)
Discontinued operations		(0.01	)		—			0.01			(0.02	)
Net income (loss)	$	0.37		$	0.13		$	0.19		$	(0.04	)
Basic weighted average common shares		48,146			49,464			51,736			51,669
Diluted weighted average common shares		51,385			52,024			54,445			51,669

(1)

“Operating expenses” and “Corporate general and administrative expenses” include a reduction ($1.6 million and less than $0.1 million) related to a state payroll tax incentive associated with an office relocation. The reduction was recorded in “Other (expense) income, net” beginning in the third quarter of 2015, but was reclassified to “Operating expenses” and “Corporate general and administrative expenses” to align the incentives with the expenses associated with the office relocation. The reclassification had no impact on “Income from continuing operations” or diluted earnings per share from continuing operations.