The following table shows a reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share.



	Three Months Ended September 30,				Nine Months Ended September 30,
(In millions, except per share amounts)	2018		2017		2018		2017
Numerators
Net income (loss) attributable to W. R. Grace & Co. shareholders	$	16.1	$	47.4	$	98.5	$	134.2
Denominators
Weighted average common shares—basic calculation	67.1		67.9		67.3		68.2
Dilutive effect of employee stock options	0.1		0.1		0.1		0.1
Weighted average common shares—diluted calculation	67.2		68.0		67.4		68.3
Basic earnings per share	$	0.24	$	0.70	$	1.46	$	1.97
Diluted earnings per share	$	0.24	$	0.70	1.46		1.96

There were 1.4 million anti-dilutive options outstanding for the three and nine months ended September 30, 2018, compared with 1.6 million and 1.5 million for the corresponding prior-year periods.

On February 5, 2015, the Company announced that its Board of Directors had authorized a share repurchase program of up to $500 million, which it completed on July 10, 2017. On February 8, 2017, the Company announced that its Board of Directors authorized an additional share repurchase program of up to $250 million, expected to be completed over the next 12 to 24 months at the discretion of management. The timing of the repurchases and the actual amount repurchased will depend on a variety of factors, including the market price of the Company’s shares, the strategic deployment of capital, and general market and economic conditions. During the nine months ended September 30, 2018 and 2017, the Company repurchased 865,698 shares and 935,435 shares of Company common stock for $60.1 million and $65.0 million, respectively, pursuant to the terms of the share repurchase programs. As of September 30, 2018, $158.7 million remained under the current authorization.