Net Income (Loss) per Share Attributable to Common Stockholders

Basic net income (loss) per share is computed by dividing net income attributable to common shareholders by the weighted-average number of common shares outstanding during the period. For the three and nine months ended September 29, 2018 and September 30, 2017, we applied the two-class method to calculate basic and diluted net income (loss) per share of common stock, as our Series A Redeemable Convertible Preferred Stock (Series A Preferred Stock) is a participating security. The two-class method is an earnings allocated formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. We compute diluted net income (loss) per common share using net income (loss) as the “control number” in determining whether potential common shares are dilutive, after giving consideration to all potentially dilutive common shares, including stock options, unvested restricted stock outstanding during the period and potential issuance of stock upon the conversion of the our Series A Preferred Stock, including accrued dividends, outstanding during the period, except where the effect of such securities would be antidilutive.

The calculations of basic and diluted net income (loss) per share and basic and dilutive weighted-average shares outstanding for the three and nine months ended September 29, 2018 and September 30, 2017 were as follows (in thousands, except per share data):



	Three Months Ended						Nine Months Ended
	September 29, 2018			September 30, 2017			September 29, 2018			September 30, 2017
Numerator:
Basic:
Net income (loss) attributable to common stockholders	$	979		$	(418	)	$	1,996		$	704
Dilutive:
Net income (loss) attributable to common stockholders	$	979		$	(418	)	$	1,996		$	704
Plus: undistributed earnings allocated to participating securities	873			—			2,384			2,055
Less: undistributed earnings reallocated to participating securities	(863		)	—			(2,362		)	(2,047		)
Net income (loss) attributable to common stockholders	$	989		$	(418	)	$	2,018		$	712

Denominator:
Weighted-average shares outstanding - basic	31,356			29,825			30,980			29,510

Dilutive impact from:
Options outstanding	1,899			1,962			1,944			1,869
Restricted stock units	625			734			709			706
Weighted-average shares outstanding - dilutive	33,880			32,521			33,633			32,085

Net income (loss) per share attributable to common stockholders (Basic):	$	0.03		$	(0.01	)	$	0.06		$	0.02
Net income (loss) per share attributable to common stockholders (Diluted):	$	0.03		$	(0.01	)	$	0.06		$	0.02

The following equity shares were excluded from the calculation of diluted net income per share attributable to common stockholders because their effect would have been antidilutive for the periods presented (in thousands):



	Three Months Ended		Nine Months Ended
	September 29, 2018	September 30, 2017	September 29, 2018	September 30, 2017
Stock options	568	1,385	843	1,334
Restricted stock units	1,048	184	808	108
Series A Redeemable Convertible Preferred Stock (as converted to common stock)	4,983	4,724	4,983	4,724

The Series A Preferred Stock is considered antidilutive due to the fact that the two-class method was more dilutive when calculating dilutive net income per share attributable to common stockholders.