14. 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):


	Year Ended
	December 31,
	2018		2017		2016
Numerator:
Net income (loss)	$	(7,175)	$	1,457	$	24,685
Loss (income) attributable to noncontrolling interests		2,715		(175)		(3,160)
Preferred stock dividends		(16,666)		—		—
Earnings attributable to participating securities		(947)		(593)		3,160
Net income (loss) available to common stockholders after allocation of participating securities	$	(22,073)	$	689	$	24,685
Denominator:
Weighted average shares outstanding - basic		50,433		48,381		46,206
Effect of Class A partnership units		—		6,696		6,783
Effect of Class O units and options to purchase Class A common stock on an "as if" converted basis		—		779		973
Weighted average shares outstanding - diluted		50,433		55,856		53,962

Basic net income (loss) per share	$	(0.44)	$	0.01	$	0.47

Diluted net income (loss) per share	$	(0.44)	$	0.01	$	0.46

Note: The table above does not include Class A partnership units of 6.7 million for the year ended December 31, 2018, 0.4 million reflecting the effects of Class O units and options to purchase common stock on an "as if" converted basis for the year ended December 31, 2018, and 3.5 million reflecting the effects of Series B Convertible preferred stock on an “as if” converted basis for the year ended December 31, 2018, as their respective inclusion would have been antidilutive.