Elan Completes Demerger of Prothena Corporation

Elan Corporation, plc

today announced completion of the separation of a substantial portion of its drug discovery business (the Prothena Business) into a new independent, publicly traded company, Prothena Corporation plc (Prothena). Prothena, which is incorporated in Ireland, today commenced trading on the NASDAQ Global Market under the ticker symbol “PRTA”. Under the terms of the demerger, Elan shareholders on the register on December 14, 2012, the record date, received 1 Prothena ordinary share for every 41 Elan ordinary shares or ADSs held. In addition a wholly owned subsidiary of Elan subscribed $26 million and received Prothena shares representing 18% of the total outstanding ordinary shares of Prothena (as calculated immediately following the subscription