Quote from nitro:
It is very difficlut to discuss these systems that were developed for gaming to trading situations because in gamming the payout is always known. In trading, the payout is unknown unless you always take profit targets and stop losses in a completely static way (say you always take +4 ES PT and always take -1.5 ES SL or any static variation thereof) probably a losing proposition in "the long run".
Martingale Betting Systems (MBS) are also known as negative progression betting. Positive progression (Parlay) is where units are doubled after wins and reduced to single units after loss. Flat progression is obvious. Negative and Positive Progression betting systems assume "games" that are not independent trials, like BlackJack where the game has memory. If a game has no memory (each trial is independent) then no amount of money management will help. It also assumes that the strategy is static as in the case of BJ (the cards in the deck don't shift based on all bets,) a situation that is definitely not true in trading, as anyone that has taken a system live can attest to: The "opponent" is always adjusting to "your" adjustments and markets amazingly count only those that enter them with real positions, i.e., increases or decreases open interest.
Further, even in the cases where there is memory (like trading certain markets, some more than others,) these betting strategies only affect players or traders "in the long run." Many on ET are investors, and are not professional traders who have many many trades per year. Therefore, few will place enough bets in their lifetimes to satisfy statistical criteria for "the long run."
In short, I think it is incredibly hard to know how much to bet in a given situation reliably and you can probably embed any question about trading systems in that question.
nitro