The decision is likely to hinge on whether Mr Kengeter is charged by prosecutors for allegations of insider trading, sources told Reuters last week - claims that he has insisted will "turn out to be unfounded". Proving themselves as standalone businesses has been key for Deutsche Boerse and the LSE since the European Commission killed their plans for a £24bn merger in March. The tie-up would have created a " de facto monopoly in the markets for clearing fixed income instruments", according to EU Commissioner Margrethe Vestager.