I did some artificial intelligence stuff at university, Neural nets, hidden markov models, gaussian mixed models, etc. I think they are nice toys for academics, but not so good at making money in the stock market. The short and medium term movements of the stock market is random (doing a Fourier transform on a typical stock price results in a flat line, just like white noise...), it is only in the long term that the market follows earnings. Even if the market is slightly non-random, the profits gets eaten up by transaction costs so you end up flat or negative.
