If CFDs are a contract with the broker and there's no central market aside from the clients and the broker. Is that likely to mean that the volume showing bar by bar [for a stock for example] is the volume traded WITHIN the brokerage [the sum total of trades between broker and clients] OR do they port in volume from futures or something??

Part of what I'm aiming for is to find out if a CFD account [DMA CFD with IB] would be suitable for learning the DOM. The aggregate feed from IB and it's suitablility for learning the DOM is I guess another question for another thread

I contacted the Broker in this case IG Markets. I wasn't really expecting a straight answer, but #I think# I got one 'The volume indicates the amount traded on the exchange for the share. It is not transactions between IG and its clients' - they said.

I thought the answer would be something less simple.