資金管理的一個關鍵組成部分就是5%原則。其實就是，永遠不要在同一時間把超過交易賬戶總資金5%的資金放到風險上。其原理是當我們獲得損失的時候（任何人都會有損失出現，這是毋庸置疑的），這些損失將會比較小並且容易處理，反之則不然。
然而在很多時候，這條規則被錯誤的解釋為每筆交易投入5%的資金，這個解釋是不準確的。
這裡的5%是指賬戶總資產的風險比例，不是指在單一交易中投入的交易資金量。因此，如果你有一單交易在進行中，5%是投入的最高保證金風險。如果你有兩單，五單或者十單交易在進行，這些交易共同止損的最高金額也是5%。
設想一下，如果這個規則是指每單交易的最高保證金風險都是5%，一個交易員就可以在這個規則下有五單最高風險是5%的交易。那麼什麼能阻止一個交易員開十單並且每單的最高風險都是5%呢?
此規則必須有一部分能阻止交易員過度槓桿借貸且保證任何時候都是5%風險。另外，就像我們從前面那個每單交易5%的例子中看到的，有五單這樣的交易員就有25%的賬戶金額處於風險之中，而有十單這樣交易的交易員的總賬戶金額的50%就在風險中。
很明顯，這都不是謹慎的交易員願意看到的情況。
Clarifying the 5% Money Management Rule
One of the key components of Money Management is the 5% rule. That is, never put more than 5% of the trading account at risk at any one time. The rationale behind this is that when we have losses (and we WILL have losses, make no mistake about that) they will be small and manageable as opposed to large and catastrophic.
Oftentimes however, this rule is erroneously interpreted as meaning 5% per trade. This is not accurate.
The 5% rule pertains to the TOTAL amount of the account balance at risk at any one time...NOT on any individual trade. So, if you have one trade open, 5% is the maximum allowable risk. If you have two trades open or five trades open or ten trades open, the maximum that could be lost if the stops on all of the trades triggered at the same time is 5%.
Think of it this way, if the rule were 5% pertrade, a trader could open five trades risking 5% on each trade and still be within the rules. What would prevent a trader from opening up ten trades and only risking 5% on each one?
There has to be something that prevents the trader from over leveraging their account and that something is the “5% risk at any one time” part of the rule. Otherwise, as you can see from the previous 5% per trade example, the trader with five trades with 5% account risk on each one would have 25% of their account at risk and the trader with ten trades would have had 50% of their account at risk.
Clearly, neither of those would be a situation in which a prudent trader would want to find themselves.
本文翻譯由兄弟財經提供
文章來源：http://www.forexcycle.com/forex-trading/35624-clarifying-the-5-money-management-rule.html