Alexion Pharmaceuticals, Inc. (NASDAQ: ALXN) (Alexion or the Company) today announced that the Company’s Board of Directors has authorized the repurchase of up to $400 million of Alexion common stock. Under the program, purchases may be made from time to time on the open market, or through privately negotiated transactions, block transactions, or other techniques, as determined by the Company’s management and in accordance with prevailing market conditions and the requirements of the Securities and Exchange Commission. Alexion expects to fund all purchases from cash on hand and future cash flows from operations. The Board’s authorization is open-ended and does not establish a timeframe for the purchases. The Company is not obligated to acquire a particular number of shares, and the program may be discontinued at any time at the Company’s discretion. About Alexion Alexion Pharmaceuticals, Inc. is a biopharmaceutical company focused on serving patients with severe and ultra-rare disorders through the innovation, development and commercialization of life-transforming therapeutic products. Alexion is the global leader in complement inhibition and has developed and markets Soliris® (eculizumab) as a treatment for patients with PNH and aHUS, two debilitating, ultra-rare and life-threatening disorders caused by chronic uncontrolled complement activation. Soliris is currently approved in more than 40 countries for the treatment of PNH, and in the United States and the European Union for the treatment of aHUS. Alexion is evaluating other potential indications for Soliris and is developing four other highly innovative biotechnology product candidates. This press release and further information about Alexion Pharmaceuticals, Inc. can be found at: www.alexionpharma.com. [ALXN-G] Safe Harbor Statement This news release contains forward-looking statements, including statements related to the funding, timing and scope of the Company's stock repurchase program. Forward-looking statements are subject to factors that may cause Alexion's results and plans to differ from those expected, including for example, then current market conditions, anticipated cash flow and a variety of other factors and risks set forth from time to time in Alexion's filings with the US Securities and Exchange Commission, including but not limited to the risks discussed in Alexion's Quarterly Report on Form 10-Q for the period ended September 30, 2012 and in our other filings with the US Securities and Exchange Commission. Alexion does not intend to update any of these forward-looking statements to reflect events or circumstances after the date hereof, except when a duty arises under law.