The calculations of basic and diluted income per share attributable to CBRE Group, Inc. shareholders are as follows (dollars in thousands, except share data):

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
		2019		2018		2019		2018
Basic Income Per Share
Net income attributable to CBRE Group, Inc. shareholders	$	256,599	$	290,469	$	644,739	$	669,424
Weighted average shares outstanding for basic income per share		336,203,747		339,477,316		336,149,719		339,151,807
Basic income per share attributable to CBRE Group, Inc. shareholders	$	0.76	$	0.86	$	1.92	$	1.97
Diluted Income Per Share
Net income attributable to CBRE Group, Inc. shareholders	$	256,599	$	290,469	$	644,739	$	669,424
Weighted average shares outstanding for basic income per share:		336,203,747		339,477,316		336,149,719		339,151,807
Dilutive effect of contingently issuable shares		4,896,435		4,256,631		4,440,288		4,114,910
Dilutive effect of stock options		—		—		—		523
Weighted average shares outstanding for diluted income per share		341,100,182		343,733,947		340,590,007		343,267,240
Diluted income per share attributable to CBRE Group, Inc. shareholders	$	0.75	$	0.85	$	1.89	$	1.95

For the three and nine months ended September 30, 2019, 320,154 and 447,687, respectively, of contingently issuable shares were excluded from the computation of diluted income per share because their inclusion would have had an anti-dilutive effect.

For the three and nine months ended September 30, 2018, 34,470 and 28,922, respectively, of contingently issuable shares were excluded from the computation of diluted income per share because their inclusion would have had an anti-dilutive effect.

In October 2016, our board of directors authorized the company to repurchase up to an aggregate of $250.0 million of our Class A common stock over three years. Through December 31, 2018, we had spent $161.0 million to repurchase 3,980,656 shares of our Class A common stock with an average price paid per share of $40.43. During the month of January 2019, we spent $45.1 million to repurchase an additional 1,144,449 shares of our Class A common stock with an average price paid per share of $39.38.

In February 2019, our board of directors authorized a new program for the company to repurchase up to $300.0 million of our Class A common stock over three years, effective March 11, 2019. The previous program terminated upon the effectiveness of the new program. In August 2019, our board of directors authorized an additional $100.0 million under our new program, bringing the total authorized amount under the new program to a total of $400.0 million. During the three months ended September 30, 2019, we spent $49.0 million to repurchase an additional 932,973 shares of our Class A common stock with an average price paid per share of $52.50.