The battle for London's equity trading crown may be lost, but the battle for the multi-trillion dollar over-the-counter derivatives market may just be getting started.

"We have had a mild skirmish when it comes to equities, we now have a massive battle coming up for derivatives," according to Alasdair Haynes, CEO of Aquis Exchange.

The question is whether London will be able to maintain market share, or will swaps trading have to move to the US. There is a potential three-way fight between the EU, UK and the US emerging for control of this highly lucrative market for those derivatives, he said.