The short answer is YES volumes are down you only have to look at the turnover levels on global exchanges, this is primarily as a result of the following:
1. Investors loosing money and scared of loosing more
2. Investment banks (prime brokers and stock lenders) not lending money to hedge funds
3. People withdrawing money from hedge funds and their superannuation (in oct-dec $298 billion was withdrawn from hedge funds in the US)
This has an effect on all brokers and CFD providers in that the majority charge on a % commission basis which in some cases is factored into the spread. When prices a lower the percentage commission earned is lower, typically people wont buy more just the same amount at a cheaper price.
Im not sure if it will effect the behavior or margins but what it will most certainly effect is the profitability of brokers and CFD providers, we have already see CMC cut a number of staff globally (refer to link below).
David Trew leaves CMC Markets after overhaul | The Australian
The current market will sort out the brokers and CFD providers that have themselves leveraged off a bull market, it is likely that you will find small CFD providers and brokers consolidate or simply shut down.
I would advise that you review at the annual accounts of you CFD provider to ensure that they have sufficient retained earnings to withstand defaults and a market downturn.
