Binary bets have a price between 0 and 100.
When the bet closes it will close at either 0 or 100.
Eg. If you buy 'FTSE to close up' whilst the market is flat you may get a price around 55.
Market starts to rally and closes +ve. The bet closes at 100 as it was 'true' so your profit is 100-55= 45 * stake size.
If however the FTSE fell and closed -ve, then the bet would expire at 0 as it was 'false' so your loss would be 55 * stake size.
They work the same way as conventional sb's, ie. you can buy or sell each price and close your positions before expiry.
They is much volatility in the prices, just a few points move up or down can cause a 20 or 30 point move in a binary price.
They are good in a way that you know exactly what your risk is as soon as you open the bet, as the price you buy at, is the risk in points if it closes at 0.
As well as index up or down they offer point ranges, eg up/down 0-10 points, 10-20 points, up/down>30 etc.
Good opportunities 15 mins or so before expiry if the price is close to a boundary (say 25 points up and in an uptrend) - you could get a good price on a finish up >30 points.
As far as I'm aware IG are the only ones who do binaries at present - they have started a new site dedicated to binaries:
www.binarybet.com with minimum bet size of £1 if you want to have a go for little expense.
Bear in mind though that I believe IG are making a packet out of binary bets so be careful. If you have some sensible rules you should be ok. I only trade at prices 25 or below to limit my risk, playing the reversals mainly.
Hope you understand my waffle, having read it again, it seems a bit confusing
