A.G. this reminds of something that I read, happened in U.S. At some big trading firm there was a contest to predict Dow Jones value in 2 months or something like that. There were like 50 participants. The person who got the closest to actual value was the person who used Random Walk model. I think this case was described by Eckhardt where he says that «most traders trade worse than random.» So your results don't suprise me at all.
