Deutsche Boerse <db1gn.de> won U.S. antitrust approval to buy NYSE Euronext <nyx.n> on Thursday in a $9 billion deal that has hit serious antitrust headwinds in Europe.

The Justice Department said on Thursday that the deal, which was announced in February, won approval on condition that a Deutsche Boerse subsidiary, the International Securities Exchange, divest its 31.5 percent interest in Direct Edge.

Direct Edge is the fourth-largest U.S. exchange, the department said.

Despite the divestiture, Deutsche Boerse and NYSE must continue to provide some services to Direct Edge, the department said.

In Europe, there have been weeks of negotiations during which European Union antitrust staff made clear their reservations about approving a combination of Deutsche Boerse's Eurex and NYSE Euronext's Liffe on concerns that the merged entity would have a monopoly over European listed derivatives trading.

Both Boerse and NYSE Euronext have said they would not pursue the merger if they were asked to divest either Eurex or Liffe. A formal decision by the European Commission is not expected until January or early February.

(Reporting By Diane Bartz; Editing by Gerald E. McCormick)