The European Commission said Deutsche Boerse and NYSE Euronext, which unveiled the deal to create the world's biggest stock exchange in February last year, had not done enough to address its concerns.

"The merger between Deutsche Boerse and NYSE Euronext would have led to a near-monopoly in European financial derivatives worldwide," EU Competition Commissioner Joaquin Almunia said in a statement.

"These markets are at the heart of the financial system and it is crucial for the whole European economy that they remain competitive. We tried to find a solution, but the remedies offered fell far short of resolving the concerns."

The Commission, which acts as competition regulator in the 27-member European Union, said the two exchanges together control more than 90 percent of global dealing in European exchange-traded financial derivatives.

(Reporting Foo Yun Chee; editing by Rex Merrifield)

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