For people who may not know the figures (these are from memory): In 30 years, Medallion has had only 1 down year, when they were down by 4.5% (this was around 1988 or 1989). In their entire 30 years of existence, they have averaged over 34.5% annual returns. Averaged.

I don't think that you would need that much insider information--you can just use more leverage. As a thought experiment, it's possible to earn similar returns by wiretapping any large business newspaper.

More leverage = much higher chance of getting caught.