11. Earnings per share of QTS Realty Trust, Inc.

Basic income per share is calculated by dividing the net income attributable to common shares by the weighted average number of common shares outstanding during the period. Diluted income per share adjusts basic income per share for the effects of potentially dilutive common shares. Unvested restricted stock awards contain non-forfeitable rights to dividends and thus are participating securities and are included in the computation of earnings per share pursuant to the two-class method for all periods presented. The two-class method is an earnings allocation formula that treats a participating security as having rights to undistributed earnings that would otherwise have been available to common stockholders. Accordingly, service-based restricted stock awards were included in the calculation of earnings per share using the two-class method for all periods presented.

The computation of basic and diluted net income per share is as follows (in thousands, except per share data, and unaudited):


	Three Months Ended
	March 31,
	2018		2017
Numerator:
Net income (loss)	$	(252)	$	5,568
Loss (income) attributable to noncontrolling interests		29		(691)
Preferred stock dividends		(328)		—
Earnings attributable to participating securities		(258)		(233)
Net income (loss) available to common stockholders after allocation of participating securities	$	(809)	$	4,644
Denominator:
Weighted average shares outstanding - basic		50,279		47,485
Effect of Class O units and options to purchase Class A common stock on an "as if" converted basis *		—		876
Weighted average shares outstanding - diluted		50,279		48,361

Basic net income (loss) per share	$	(0.02)	$	0.10

Diluted net income (loss) per share	$	(0.02)	$	0.10

Does not include Class A partnership units of 6.6 million and 6.8 million for the three months ended March 31, 2018 and 2017, respectively, and 0.5 million reflecting the effects of Class O units and options to purchase common stock on an "as if" converted basis for the three months ended March 31, 2018, as their respective inclusion would have been antidilutive.