EU regulators to investigate Deutsche Boerse, LSE mega deal

BRUSSELS, Sept 28 (Reuters) - EU antitrust regulators opened an investigation into Deutsche Boerse (LSE: 0H3T.L - news) 's proposed $28 billion merger with the London Stock Exchange (Other OTC: LDNXF - news) on Wednesday, saying that the deal would reduce competition in key financial market activities.

The move, which the companies previously flagged, is expected to force the stock exchanges to offer concessions to allay competition concerns.

The European Commission cited concerns about less competition in clearing where the merged company would combine the largest margin pool in the world worth 150 billion euros ($168 billion), and in derivatives.

"Financial markets provide an essential function for the European economy. We must ensure that market participants continue to have access to financial market infrastructure on competitive terms," European Competition Commissioner Margrethe Vestager said in a statement.

The Commision will rule on the proposed merger by Feb. 13, a deadline which would be extended once the companies submit concessions. ($1 = 0.8919 euros) (Reporting by Foo Yun Chee; editing by Philip Blenkinsop)