9. Earnings (Loss) per Common Share

Basic earnings (loss) per common share is computed by dividing net income attributable to Novanta Inc. after adjustment of redeemable noncontrolling interest to estimated redemption value by the weighted average number of common shares outstanding during the year. The Company recognizes changes in the redeemable noncontrolling interest redemption value by adjusting the carrying amount of the redeemable noncontrolling interest as of the end of the period to the higher of: (i) the estimated redemption value assuming the end of the period is also the redemption date or (ii) the carrying value without any redemption value adjustments. Such adjustments are recorded in retained earnings in stockholders’ equity instead of net income attributable to Novanta Inc. For both basic and diluted earnings (loss) per common share, such redemption value adjustments are included in the calculation of the numerator. For diluted earnings (loss) per common share, the denominator also includes the dilutive effect of outstanding restricted stock units, stock options and total shareholder return performance restricted stock units determined using the treasury stock method. Dilutive effects of contingently issuable shares are included in the weighted average dilutive share calculation using the treasury method when the contingencies have been resolved. For years in which net losses are generated, the dilutive potential common shares are excluded from the calculation of diluted earnings per share as the effect would be anti-dilutive.

The following table sets forth the computation of basic and diluted earnings (loss) per share (in thousands, except per share amounts):

	Year Ended December 31,
	2017			2016		2015
Numerators:
Income from continuing operations	$	62,307		$	22,003	$	35,628
Less: Net income attributable to noncontrolling interest		(2,256	)		—		—
Income from continuing operations attributable to Novanta Inc.		60,051			22,003		35,628
Less: Adjustment of redeemable noncontrolling interest to estimated redemption value (see Note 17)		(20,244	)		—		—
Income from continuing operations attributable to Novanta Inc. after adjustment of redeemable noncontrolling interest to estimated redemption value		39,807			22,003		35,628
Loss from discontinued operations		—			—		(13	)
Net income attributable to Novanta Inc. after adjustment of redeemable noncontrolling interest to estimated redemption value	$	39,807		$	22,003	$	35,615

Denominators:
Weighted average common shares outstanding— basic		34,817			34,694		34,579
Dilutive potential common shares		463			220		248
Weighted average common shares outstanding— diluted		35,280			34,914		34,827
Antidilutive common shares excluded from above		—			85		—

Basic Earnings (Loss) per Common Share:
From continuing operations	$	1.14		$	0.63	$	1.03
From discontinued operations	$	—		$	—	$	(0.00	)
Basic earnings (loss) per share attributable to Novanta Inc.	$	1.14		$	0.63	$	1.03

Diluted Earnings (Loss) per Common Share:
From continuing operations	$	1.13		$	0.63	$	1.02
From discontinued operations	$	—		$	—	$	(0.00	)
Diluted earnings (loss) per share attributable to Novanta Inc.	$	1.13		$	0.63	$	1.02

Common Stock Repurchases

In October 2013, the Company’s Board of Directors authorized a share repurchase plan under which the Company may repurchase outstanding shares of the Company’s common stock up to an aggregate amount of $10.0 million. The shares may be repurchased from time to time, at the Company’s discretion, based on ongoing assessment of the capital needs of the business, the market price of the Company’s common stock, and general market conditions. Shares may also be repurchased through an accelerated stock purchase agreement, on the open market or in privately negotiated transactions in accordance with applicable federal securities laws. Repurchases may be made under certain SEC regulations, which would permit common stock to be repurchased when the Company would otherwise be prohibited from doing so under insider trading laws. The share repurchase plan does not obligate the Company to acquire any particular amount of common stock. No time limit was set for the completion of the share repurchase program, and the program may be suspended or discontinued at any time. The Company expects to fund the share repurchases through cash on hand and future cash generated from operations. During 2017, the Company repurchased 14 thousand shares in the open market for an aggregate purchase price of $0.4 million at an average price of $26.41 per share. As of December 31, 2017, the Company had repurchased an aggregate of 296 thousand shares for an aggregate purchase price of $4.2 million at an average price of $14.05 per share.