United states securities and exchange commission

Table of Contents
BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)
F- 43
15.    Earnings per Share
Basic and diluted earnings per share are calculated as follows:
 
For the Years Ended December 31,
(In millions)
2017
2016
2015
Numerator:
Net income attributable to Biogen Inc.
$
2,539.1
$
3,702.8 $
3,547.0
Denominator:
Weighted average number of common shares outstanding
212.6
218.4
230.7
Effect of dilutive securities:
Stock options and employee stock purchase plan
0.1
0.1
0.1
Time-vested restricted stock units
0.2
0.2
0.3
Market stock units
0.1
0.1
0.1
Dilutive potential common shares
0.4
0.4
0.5
Shares used in calculating diluted earnings per share
213.0
218.8
231.2
Amounts excluded from the calculation of net income per diluted share because their effects were anti-dilutive 
were insignificant.
Earnings per share for the years ended December 31, 2017, 2016 and 2015 reflects, on a weighted average 
basis, the repurchase of 3.7 million shares, 0.7 million shares and 4.6 million shares, respectively, of our common 
stock under our share repurchase authorizations.
The adjustments related to the spin-off of our hemophilia business did not have a material impact on the 
potentially dilutive securities to be considered in the calculation of diluted earnings per share of common stock.
16.   Share-based Payments
Share-based Compensation Expense
The following table summarizes share-based compensation expense included in our consolidated statements of 
income:
 
For the Years Ended December 31,
(In millions)
2017
2016
2015
Research and development
$
74.0
$
84.5 $
88.6
Selling, general and administrative
95.7
121.7
127.3
Restructuring charges
—
(1.8)
(8.6)
Subtotal
169.7
204.4
207.3
Capitalized share-based compensation costs
(9.6)
(14.6)
(11.0)
Share-based compensation expense included in total cost
and expenses
160.1
189.8
196.3
Income tax effect
(42.8)
(54.0)
(55.8)
Share-based compensation expense included in net income
attributable to Biogen Inc.
$
117.3
$
135.8 $
140.5

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Table of Contents
BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)
F- 44
The following table summarizes share-based compensation expense associated with each of our share-based 
compensation programs:
 
For the Years Ended December 31,
(In millions)
2017
2016
2015
Market stock units
$
22.4
$
38.4 $
38.1
Time-vested restricted stock units
107.3
120.0
119.0
Cash settled performance units
18.4
16.3
22.4
Performance units
12.3
18.6
13.9
Employee stock purchase plan
9.3
11.1
13.9
Subtotal
169.7
204.4
207.3
Capitalized share-based compensation costs
(9.6)
(14.6)
(11.0)
Share-based compensation expense included in total cost
and expenses
$
160.1
$
189.8 $
196.3
As of December 31, 2017, unrecognized compensation cost related to unvested share-based compensation 
was approximately $168.0 million, net of estimated forfeitures. We expect to recognize the cost of these unvested 
awards over a weighted-average period of 1.9 years.
Spin-off Related Equity Adjustments
Pursuant to an employee matters agreement entered into in connection with the spin-off of our hemophilia 
business and the provisions of our existing share-based compensation arrangements, we made certain adjustments 
to the number and terms of our outstanding stock options, RSUs, CSPUs and other share-based awards to preserve 
the intrinsic value of the awards immediately before and after the spin-off. For purposes of the vesting of these 
equity awards, continued employment or service with Biogen or with Bioverativ was treated as continued employment 
for purposes of both Biogen’s and Bioverativ’s equity awards with the outstanding awards continuing to vest over 
their respective original vesting periods. Outstanding unvested awards for employees transferring to Bioverativ were 
converted to unvested Bioverativ awards.
Adjustments to the number of our share-based compensation awards were made using an adjustment ratio 
based upon the weighted-average closing price of our common stock for the 10 calendar days prior to the effective 
date of the spin-off and the volume-weighted average prices for the 10 calendar days of our common stock following 
the effective date of the spin-off. For stock options, the exercise prices of the awards were modified to maintain the 
pre-spin intrinsic value of the awards in relation to the post-spin stock price of Biogen. The difference between the 
fair value of the awards based upon the adjustment ratio and the opening price on the distribution date was not 
material.
Share-Based Compensation Plans
We have three share-based compensation plans pursuant to which awards are currently being made: (i) the 
Biogen Inc. 2006 Non-Employee Directors Equity Plan (2006 Directors Plan); (ii) the Biogen Inc. 2017 Omnibus 
Equity Plan (2017 Omnibus Equity Plan); and (iii) the Biogen Inc. 2015 Employee Stock Purchase Plan (2015 ESPP). 
Directors Plan
In May 2006 our shareholders approved the 2006 Directors Plan for share-based awards to our directors. 
Awards granted from the 2006 Directors Plan may include stock options, shares of restricted stock, RSUs, stock 
appreciation rights and other awards in such amounts and with such terms and conditions as may be determined by 
a committee of our Board of Directors, subject to the provisions of the plan. We have reserved a total of 1.6 million 
shares of common stock for issuance under the 2006 Directors Plan. The 2006 Directors Plan provides that awards 
other than stock options and stock appreciation rights will be counted against the total number of shares reserved 
under the plan in a 1.5-to-1 ratio. In June 2015 our shareholders approved an amendment to extend the term of the 
2006 Directors Plan until June 2025.

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