What is the 'Martingale System'

The Martingale system is a system of investing in which the dollar value of investments continually increases after losses, or the position size increases with a lowering portfolio size. The Martingale system was introduced by French mathematician Paul Pierre Levy in the 18th century.

BREAKING DOWN 'Martingale System'

The Martingale system is a very risky method of investing. The main idea behind the Martingale system is that statistically, you cannot lose all the time, and therefore, you should increase the amount allocated in investments — even if they are declining in value — in anticipation of a future increase. The Martingale system is commonly compared to betting in a casino. When a gambler using this method loses, he or she doubles the bet. By repeatedly doubling the bet when he or she loses, the gambler, in theory, will eventually even out with a win. This assumes the gambler has an unlimited supply of money to bet with, or at least enough money to make it to the winning payoff.

Basic Example of the Martingale System

To understand the basics behind the strategy, let's look at a basic example. Suppose you have a coin and engage in a betting game of either heads or tails with a starting wager of $1. There is an equal probability that the coin will land on heads or tails, and each flip is independent (the prior flip does not impact the outcome of the next flip). As long as you stick with the same call of either heads or tails, you would eventually, given an infinite amount of money, see the coin land on heads (or tails), if that's your call, and thus recoup all of your losses, plus $1. The strategy is based on the premise that only one trade is needed to turn your fortunes around.

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