London Stock Exchange plc (LDNXF)  and Deutsche Boerse AG (DBOEY)  shares fell sharply Monday as the third attempt to combine the two stock exchange operators appeared close to collapse amid demands from competition authorities in the European Union.

The LSE said late Sunday that it was unlikely to meet a demand from the EU to sell 60% of its MTS government bond trading platform in order to comply with concerns that the €29 billion ($30.1 billion) merger with the Deutsche Boerse could hamper competition in the region's financial services sector.