Equity

Total equity as of September 30, 2018, increased $1.2 billion compared to December 31, 2017. This increase was primarily due to net income attributable to Biogen Inc. of approximately $3.5 billion and a net cumulative-effect adjustment of approximately $0.5 billion recognized to retained earnings upon the adoptions of ASUs 2016-16 and 2016-01, partially offset by share repurchases totaling $3.0 billion, as described below.

For additional information on our adoption of ASUs 2016-16 and 2016-01, please read Note 1, Summary of Significant Accounting Policies - New Accounting Pronouncements, to these condensed consolidated financial statements.

Share Repurchases

In August 2018 our Board of Directors authorized a program to repurchase up to $3.5 billion of our common stock (2018 Share Repurchase Program). Our 2018 Share Repurchase Program does not have an expiration date. All share repurchases under our 2018 Share Repurchase Program will be retired. We did not repurchase any shares of our common stock under our 2018 Share Repurchase Program during the three and nine months ended September 30, 2018.

In July 2016 our Board of Directors authorized a program to repurchase up to $5.0 billion of our common stock (2016 Share Repurchase Program), which was completed as of June 30, 2018. All share repurchases under our 2016 Share Repurchase Program were retired. Under our 2016 Share Repurchase Program, we repurchased and retired 10.5 million shares of our common stock at a cost of $3.0 billion during the nine months ended September 30, 2018, and we repurchased and retired 3.7 million shares of our common stock at a cost of $1.0 billion during the nine months ended September 30, 2017. We did not repurchase any shares of our common stock under our 2016 Share Repurchase Program during the three months ended September 30, 2017.

In February 2011 our Board of Directors authorized a program to repurchase up to 20.0 million shares of our common stock (2011 Share Repurchase Program), which was completed as of March 31, 2017. Share repurchases under our 2011 Share Repurchase Program were principally used to offset common stock issuances under our share-based compensation programs. Under our 2011 Share Repurchase Program, we repurchased 1.2 million shares of our common stock at a cost of $365.4 million during the nine months ended September 30, 2017.

Noncontrolling Interests

The following table reconciles equity (deficit) attributable to noncontrolling interests (NCI):



	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
(In millions)	2018			2017			2018			2017
NCI, beginning of period	$	(7.2	)	$	(11.6	)	$	(14.7	)	$	(11.5	)
Net income (loss) attributable to NCI, net of tax	(1.5		)	—			45.2			(0.1		)
Capital contribution by noncontrolling interest	2.0			—			13.1			—
Distribution to noncontrolling interest	—			—			(50.0		)	—
Translation adjustment and other	(0.1		)	—			(0.4		)	—
NCI, end of period	$	(6.8	)	$	(11.6	)	$	(6.8	)	$	(11.6	)