NEW YORK CITY-The European Commission has blocked the proposed merger between NYSE Euronext and Frankfurt-based Deutsche Borse on Wednesday morning, citing concerns that the combination would have resulted in a “quasi-monopoly” throughout the global exchange market. In light of the decision, both companies are in discussions to terminate their merger agreement.

The $9.5 billion, all-stock deal would have given Deutsche Boerse majority ownership of the combined company. Though the deal gained approval by the boards of directors at both companies, the EU’s investigation showed that “new competitors would be unlikely to enter the market successfully enough to pose a credible competitive threat to the merged company.” The commission’s analysis focused on the effects of the merger on the markets for European financial derivatives traded on exchanges, noting that the benefits of price competition would have been “taken away” from customers.

Describing the decision as a “disappointment” and “an unrealistically narrow definition of the market,” the executive board of Duetsche Borse says the termination of the merger will stifle “future competitiveness on global financial markets.”