Traders gather at the post that trades Allergan on the floor of the New York Stock Exchange
Traders gather as NYSE Floor official Nicholas Brigandi, (C ) prepares to open Allergan stock on the floor of the New York Stock Exchange October 29, 2015. Botox maker Allergan Plc and Pfizer Inc. on Thursday confirmed they were in preliminary, friendly talks on a potential merger, a deal that would create the world's largest drugmaker. REUTERS/Brendan McDermid