21. Basic and Diluted Income Per Common Share

Earnings per share ("EPS") is calculated using the two-class method, which allocates earnings among common stock and participating securities to calculate EPS when an entity's capital structure includes either two or more classes of common stock or common stock and participating securities. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are participating securities. As such, shares of any unvested restricted stock of the Company are considered participating securities. The dilutive effect of options and their equivalents (including non-vested stock issued under stock-based compensation plans), is computed using the "treasury" method as this measurement was determined to be more dilutive between the two available methods in each period.

The following potential weighted common shares were excluded from diluted EPS for the three months ended June 30, 2019 due to the antidilutive impact to diluted EPS: 2,168,454 for outstanding warrants to purchase the Company's stock, 2,088,567 for convertible preferred stock, and 582,422 of unvested restricted stock.

The following potential weighted common shares were excluded from diluted EPS for the six months ended June 30, 2019 due to the antidilutive impact to diluted EPS: 2,168,454 for outstanding warrants to purchase the Company's stock, and 486,627 of unvested restricted stock.

The following potential weighted common shares were excluded from diluted EPS for the three and six months ended June 30, 2018 as the shares were antidilutive: 2,019,972 for outstanding warrants to purchase the Company's stock and 4,787,602 for convertible preferred stock.

The following table presents a reconciliation of net income (loss) used in basic and diluted EPS calculations (in millions, except per share amounts):



	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Net income attributable to common stock and participating preferred stockholders	$	9.0		$	54.7		$	7.4		$	19.0
Earnings allocable to common shares:

Numerator for basic and diluted earnings per share
Participating shares at end of period:
Weighted-average common stock outstanding	45.6			44.2			45.2			44.1
Unvested restricted stock	0.6			0.4			0.5			0.3
Preferred stock (as-converted basis)	2.1			4.8			2.2			4.8
Total	48.3			49.4			47.9			49.2

Percentage of loss allocated to:
Common stock	94.5		%	89.5		%	94.4		%	89.6		%
Unvested restricted stock	1.2		%	0.8		%	1.0		%	0.6		%
Preferred stock	4.3		%	9.7		%	4.6		%	9.8		%

Net Income attributable to common stock, basic	$	8.5		$	48.9		$	7.0		$	17.0

Distributed and Undistributed earnings to Common Shareholders:
Effect of assumed shares under treasury stock method for stock options and restricted shares and if-converted method for convertible instruments	(1.4		)	0.1			(2.4		)	—
Net Income attributable to common stock, diluted	$	7.1		$	49.0		$	4.6		$	17.0

Denominator for basic and dilutive earnings per share
Weighted average common shares outstanding - basic	45.6			44.2			45.2			44.1
Effect of assumed shares under treasury stock method for stock options and restricted shares and if-converted method for convertible instruments	12.5			1.3			14.7			1.2
Weighted average common shares outstanding - diluted	58.1			45.5			59.9			45.3

Net income attributable to participating security holders - Basic	$	0.19		$	1.11		$	0.15		$	0.39
Net income attributable to participating security holders - Diluted	$	0.12		$	1.08		$	0.08		$	0.38