UK competition watchdog launches probe of exchange operator CME's deal to buy NEX

(Reuters) - Britain's antitrust watchdog is launching an investigation into whether U.S. exchange operator CME Group's <CME.O> $5.5 billion (4.21 billion pounds) acquisition of NEX Group <NXGN.L> will lessen competition, the regulator said on Thursday.

CME agreed to buy NEX in March, creating a cross-border powerhouse for investors trading in the multi-trillion dollar foreign exchange and government debt markets.

The Competition and Markets Authority (CMA) said it would announce by Nov. 8 whether it will refer the deal for an in-depth investigation.

(Reporting by Arathy S Nair in Bengaluru; Editing by Jan Harvey)