Biogen Inc. (BIIB) - Get Report is on the hunt for a successor to chief financial officer Paul Clancy, who will be leaving the company to join Alexion Pharmaceuticals Inc. (ALXN) - Get Report .

In an announcement after the market close on Tuesday, June 13, Biogen said chief accounting officer Greg Covino will serve as interim principal financial officer as the Cambridge, Mass.-based firm searches for a new finance chief.

Clancy, whose career at Biogen has spanned more than 16 years, will stay with the firm through the end of the month. Clancy joined Biogen in 2001 and has held roles including vice president of business planning, portfolio management and U.S. marketing, and senior vice president of finance. Previously, Clancy was at PepsiCo Inc. (PEP) - Get Report .

He will join New Haven, Conn.-based Alexion on July 10 and assume the CFO post on July 31, succeeding Dave Anderson, who will become a senior adviser to CEO Ludwig Hantson, according to a news release issued by Alexion. Anderson will remain at Alexion through end-August.

Alexion on May 23 announced Anderson's planned departure at the end of August as well as other changes to its leadership team. On June 1, Alexion said it has appointed John Orloff, M.D. as head of research & development, Anne-Marie Law as chief human resources officer and Indrani Lall Franchini, J.D. as chief compliance officer.

Alexion in March installed Hantson as CEO.

Shares of Alexion rose 4.2% in after-hours trading to $112.56 on Tuesday, after finishing the trading session at $108, up 1.1%. Biogen shares were changing hands at $257.55, down 1.5%, after ending the trading session at $261.42, down 0.3%.

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