Your mistake Flemster was probably shorting stocks that are considered safe, during a period of uncertainty and volatility...you would think that they look overvalued but investment funds flowing out of more risky mining stocks etc. have flooded the market and given yield stocks a great run.
I've only traded CFD's on the AUD/USD and Gold because they have small spreads and low borrowing and holding costs..I haven't tried stocks but if I did I would not be leaving positions open overnight as anything could happen the next morning..that would be my biggest concern anyway.