If you buy £10,000 of Barclays using a traditional stockbroker you would have to pay the full amount in cash. But if you bought the equivalent sized position using a spread bet you would be required to only pay a deposit of say 10% or £1,000, see - How 'Margin' works

Assume you had £10,000 and bought the position using spread bets putting up a deposit of just £1,000. The balance of £9,000 would be left in your deposit account earning interest. And it is this interest payment that is the cost of carry.

Having a good broker won't guarantee you profits but a bad broker will probably lead to losses as a combination of their gamesmanship and suspect software takes its financial toll.

So who do I recommend?

Simple, the 2 brokers I personally use for my own spread betting (and I've used them for years) -

• Read my side-by-side review of the 2 best spread bet brokers