The purpose of the Kelly Criterion is to either minimize the time it takes to reach a target level or to maximize the portfolio growth rate by adjusting the amount of capital used per trade. It is very aggressive and can make for a very volatile portfolio, but you won't go bankrupt as the dollar amount invested diminishes with each losing trading (and increases with each winning one). Ralph Vince wrote some books about using it from the traders point of view and a recent book called Fortune's Formula discusses it from a historical perspective. It's a good read. BTW, Dr. Z's Beat the Racetrack is available on Amazon for $90 to $180 used. I'm holding on to my copy.