Money Management - What is it and why do we need it?
Every trader needs an edge in order to make money from the markets in the long run. That edge differs from trader to trader and it is depending on his trading style and on what he trades. The edge for example is different for a market maker in stocks than that for a long term trend follower in futures markets. Without it, he will be an easy target and he will gradually lose his capital. But the edge by itself alone is not a passport to success.
Overexploit a small edge and you are going to end in the poorhouse.
What do I mean by this sentence? Trading is a tough job and whatever edge a trader might have is usually small. If there were big opportunities for easy profits then those would be easy spotted and exploited by many and they would cease to exist. Having this small edge doesn't mean luck steps out of the equation. Luck will still be the major short term's determining factor. Luck will tell you if your bank account's balance will head north or south in the short term. In the long term however your edge is the only thing that it will matter. If it is positive you will earn money. If it is very positive you will earn big money. The bursts of good luck and bad luck will cancel its other in the long run and all that will be left is the edge. BUT, there is one big but

. If you played big, in other words if you were overexposed then a bad luck's burst will catch you in the short term and it will not let you exploit your long term advantage.
Think about it. It is very simple!!! If you risk too much then you will not 'live' long enough to exploit your edge. You will have a winning system but eventually you will have manage to end up broke. That's were Money Management enters the equation. Money management will simply tell you how much you can afford to risk for exploiting an edge. It will assure that you will take the cream from an edge without in the meantime ending up broke from a portion of bad luck.
Every successful trader uses a version of the money management concept to control his risks. You can hear someone say. I never risk more than 2% of my capital in every trade. What he means is that the size of his position ensures that even if his stop loss order is triggered he will not lose more than 2% of his total capital. This is a simple way for ensuring that a losing streak won't hurt you much. You will survive to trade the next day.
A concept that you will hear about in money management is the famous 'Kelly Fraction'. Often you will hear criticism about Kelly and in most cases it will be something like this: "Kelly fraction is very dangerous to trade. You will end up broke using it.". Let's sort things out by first stating what Kelly fraction is. Every trader following a trading system has a summary of that system's statistics. That statistics describe the profitability, in other words the edge of this system and are easily available if you test your system in any back testing platform. From that statistics you can extract a number, 'the Kelly Fraction'. The Kelly fraction is the absolute maximum percentage of your capital that you can risk in every trade. Read this statement carefully. The concept of Kelly fraction in trading is not advising you to risk that percentage of your capital in every trade but is advising you never to exceed that percentage because you have nothing to gain by doing so.
Having calculated this 'Kelly fraction' for your system and assuming that your system will keep working in the future, there is only one question to answer. How aggressive you want to be? Can you sustain a big drawdown in your equity curve in exchange for a chance to achieve your goal sooner? Then by all means allocate a percentage close to the Kelly Fraction in every trade. But be prepared mentally for a very tough ride!!! A rule of thumb may look something like this.
Suppose you have calculated you Kelly fraction to be 10%.
Very Aggressive trader : Risk 7% of your trading capital in every trade (in other words 0.7 * Kelly).
Aggressive trader : Risk 5% of your trading capital in every trade (in other words 0.5 * Kelly).
Conservative trader : Risk 1% - 2% of your trading capital in every trade (in other words 0.1 - 0.2 * Kelly).
Very Conservative trader : Put your money in the bank

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