For the Vodafone sceptic:

Scenario 1 for the Vodafone sceptic

You've heard a whisper, read a news item, looked at the new phone model, whatever - and you just don't fancy Vodafone. You do more research, look at the up-coming competition and it confirms your gut feeling. You believe Vodafone, with a Spread of 136 - 137 is over-valued.

You place a bet on the Vodafone price going down, £10 a point, starting at 136.

Two weeks later it's bad news for Vodafone, good news for you. The price has dropped and the Spread is now 116 - 117. You close your position at 117, a profit for you of 19 points at £10 per point, £190.

But let's just suppose…

Scenario 2 for the Vodafone sceptic

Same situation. You have taken a long hard look at Vodafone and you are not impressed. With a spread of 136 - 137 you think the share is overvalued and will go down in the not-too-distant future.

You place your £10-a-point 'sell' bet and sit tight. The clock starts ticking at 136.

Calamity! Suddenly the market loves Vodafone and the price rises to 155 -156. Your 15 per cent Stop-Loss kicks in, and your bet is closed at 156. You owe the man £200.

(You will notice that in this scenario we added 19p, not 20p, to the spread price. That's because a 15 per cent Stop-Loss would have been triggered at 155 - 156).