Equity

Total equity as of March 31, 2018, increased $1.4 billion compared to December 31, 2017. This increase was primarily driven by net income attributable to Biogen Inc. of approximately $1.2 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 $250.0 million, as described below.

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

Share Repurchases

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). Our 2016 Share Repurchase Program does not have an expiration date. All share repurchases under our 2016 Share Repurchase Program will be retired. Under our 2016 Share Repurchase Program, we repurchased and retired 0.9 million shares of common stock at a cost of $250.0 million during the three months ended March 31, 2018, and we repurchased and retired 0.8 million shares of common stock at a cost of $218.2 million during the three months ended March 31, 2017. As of March 31, 2018, approximately $2.8 billion remains available for share repurchase under our 2016 Share Repurchase Program.

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

Noncontrolling Interests

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



	For the Three Months Ended March 31,
(In millions)	2018			2017
NCI, beginning of period	$	(14.7	)	$	(11.5	)
Net income (loss) attributable to NCI, net of tax	(1.7		)	(0.1		)
Translation adjustment and other	0.2			—
NCI, end of period	$	(16.2	)	$	(11.6	)