Net Income (Loss) Per Share

6 Months Ended

Jun. 30, 2020

Net income (loss) per share was calculated as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
(in millions, except per share data)	2020		2019		2020		2019
Net income (loss) - basic and diluted	$	79.6	$	51.3	$	117.0	$	(50.8)
Weighted-average common shares outstanding:
Basic	93.0		91.4		92.8		91.2
Effect of dilutive securities:
Stock options	2.6		2.6		2.5		—
Restricted stock	0.5		0.3		0.5		—
2024 Notes	2.1		0.5		1.8		—
Diluted	98.2		94.8		97.6		91.2
Net income (loss) per share:
Basic	$	0.86	$	0.56	$	1.26	$	(0.56)
Diluted	$	0.81	$	0.54	$	1.20	$	(0.56)

Convertible debt instruments that may be settled entirely or partly in cash (such as the 2024 Notes) may, in certain circumstances where the borrower has the ability and intent to settle in cash, be accounted for under the treasury stock method. We issued the 2024 Notes with a combination settlement feature, which we have the ability and intent to use upon conversion of the 2024 Notes, to settle the principal amount of debt for cash and the excess of the principal portion in shares of our common stock. As a result, of the approximately 6.8 million shares underlying the 2024 Notes, only the shares required to settle the excess of the principal portion are considered under the treasury stock method.

Shares which have been excluded from diluted per share amounts because their effect would have been anti-dilutive were 2.2 million and 1.4 million for the three and six months ended June 30, 2020, respectively, and 2.3 million and 8.5 million for the three and six months ended June 30, 2019, respectively.