LiamH - You are pretty much right on the relationship between SB prices and the underlying market - for the various monthly contracts they can be many points off the market when the market is trading. When the market is closed, the SB prices are reflections of the Futures prices and the bias can be much greater: e.g. at ths minute, the FTSE100 is at 4980.2, where it ceased trading Friday at 16:30hrs. At that point, Fins were quoting the October FTSE100 market at mid-price 4999, that is, 5003 to buy, 4995 to sell, the familiar 20pts or so bias to the upside. this makes the TA difficult but not impossible, as the SB prices generally move in line with the underlying index - so if the FTSE100 itself goes up 100pts, so does the SB market.
However, at this minute, although the FTSE100 market itself is closed, Fins are offering (for orders only, not trades) the Oct FTSE100 spreadbet at 4831 to 4839. This is down 164pts from 16:30hrs Friday, so they are showing a belief that the market will drop substantially on tomorrow's open from Friday's close.
If your TA of the actual FTSE100 suggests support at say 4875, and you put a stop there on a Fins long position, even allowing for a 20pts bias, you are already stopped out. So not only do you have to allow for the bias, you have to allow for out-of-hours volatility as well. Its quite possible that by the time we get to 0800hrs tomorrow, the FTSE will open in London at exactly where it closed Friday afternoon, but the out-of-hours movements will have killed so many bulls.
Short-term spreadbetting, intra-day or aciross 2 days, is very tough to win at. Longer-term, over a week or longer, the job is easier, as the SB firms can't stand off 164pts from the market for more than a weekend or overnight, but its still no picnic. Trade small until you're consistent, stay in the game until you can win it.
