Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Market and Stockholder Information

Our common stock trades on The Nasdaq Global Select Market under the symbol “BIIB.” The following table shows the high and low sales price for our common stock as reported by The Nasdaq Global Select Market for each quarter in the years ended December 31, 2017 and 2016:

The sales prices in the first quarter of 2017 in the tables above have been adjusted for the impact of the spin-off of our hemophilia business. For additional information on the spin-off of our hemophilia business, please read Note 3, Hemophilia Spin-Off, to our consolidated financial statements included in this report.

As of January 26, 2018, there were approximately 665 shareholders of record of our common stock.

Dividends

We have not paid cash dividends since our inception. While we historically have not paid cash dividends and do not have a current intention to pay cash dividends, we continually review our capital allocation strategies, including, among other things, payment of cash dividends, stock repurchases or acquisitions.

Issuer Purchases of Equity Securities

In July 2016 our Board of Directors authorized our 2016 Share Repurchase Program, which is a program to repurchase up to $5.0 billion of our common stock. This authorization does not have an expiration date. All share repurchases under this authorization will be retired.

During the year ended December 31, 2017, we repurchased and retired approximately 3.7 million shares of common stock at a cost of $1.0 billion under our 2016 Share Repurchase Program. As of December 31, 2017, approximately $3.0 billion remains available for share repurchases 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 our common stock (2011 Share Repurchase Program). Shares repurchased under this authorization were principally used to offset common stock issuances under our share-based compensation programs.

During the year ended December 31, 2017, we repurchased approximately 1.2 million shares of common stock at a cost of $365.4 million under our 2011 Share Repurchase Program. Our 2011 Share Repurchase Program was completed as of March 31, 2017.

Stock Performance Graph

The graph below compares the five-year cumulative total stockholder return on our common stock, the S&P 500 Index, the Nasdaq Pharmaceutical Index and the Nasdaq Biotechnology Index assuming the investment of $100.00 on December 31, 2012 with dividends being reinvested. The stock price performance in the graph below is not necessarily indicative of future price performance. The table below reflects the stock prices as adjusted for the spin-off of our hemophilia business, which was effected on February 1, 2017. For additional information on the spin-off of our hemophilia business, please read Note 3, Hemophilia Spin-Off, to our consolidated financial statements included in this report.