Читать книгу Binary Trading - John Piper - Страница 30

If we buy at 15 the odds of success are against us and if those odds are born out we will only win one time out of every eight times. To calculate that I have assumed the spread at 10/15 and taken the mid-point which is 12.5. At 12.5 we risk that amount with a potential gain of 87.5 (100 – 12.5). That is exactly equal to odds of 8 to 1.

So we lose seven times at £10 per point.

Losses 7 x £150 (15 x £10) = £1050

We win once and make 85 points (100 – 15) = £850

Clearly this will not do

We are down £200 and the reason is the spread. But even without the spread we would still only break even. The reason for this is that betting in this way does not offer good value.

To work out the cost of the spread you take the cost of each bet (15) and deduct from that the cost needed to reflect the probability of 8 to 1 – that price is 12.5. So every time you trade the cost of the spread is 2.5 (15 less 12.5). Note that this is half of the actual spread of 5 points (15 less 10). We do each trade at £10 per point so each trade costs us £25 in terms of the spread. Eight trades at £25 for each one equals £200, which is our overall loss on the exercise.