Does 2 Percent Protect your Capital from Drawdowns?
The 2 Percent Rule says:
NEVER RISK MORE THAN 2 PERCENT OF YOUR CAPITAL ON ANY ONE STOCK.
But this assumes that all stocks move independently of each other. In the real world we are not faced with a perfect binomial distribution:
- gains are not all equal;
- some losses are bigger than others — stop losses occasionally fail when prices gap up/down;
- probabilities vary; and
- outcomes influence each other — when stocks fall, they tend to fall together.
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The biggest flaw in most risk management systems is that stock movements influence each other. Individual trades are not independent. Markets march in unison and individual stocks follow. Of course there are mavericks: stocks that rise in a bear market or collapse in the middle of a bull market, but they are a handful. The majority follow like sheep.
Thomas Dorsey in Point & Figure Charting gives an example of the risks affecting a typical stock:
The risk of the market moving against you is clearly the biggest single risk factor. How do we protect against this?
The 2 percent rule alone will not protect you if you are holding a large number of banking stocks during an asset bubble; insurance stocks during a natural disaster; or technology stocks during the Dotcom boom. We need a quick rule of thumb to measure our exposure to a particular industry or market.
Limit your exposure to specific industry sectors. Not all sectors are created equal, however. Industry groups in the (ICB or GICS) Raw Materials sector have fairly low correlation, and can be treated as separate sectors, while industry groups in most other sectors should be treated as a single unit.
We can see from the above chart that Chemicals and Containers & Packaging tend to move in unison and should possibly be treated as one industry sector, but other indexes shown are sufficiently independent to be treated separately.
As a rule of thumb, limit your Total Capital at Risk in any one industry sector to 3 times your (maximum) Capital at Risk per stock (e.g. 6% of your capital if you are using the 2 percent rule).
This does not mean that you are limited to holding 3 stocks in any one sector. You may buy a fourth stock when one of your initial 3 trades is no longer at risk (when you have moved the stop up above your breakeven point on the trade); and a fifth when you have covered your risk on another trade; and so on.
Just be careful not to move your stops up too quickly. In your haste you may be stopped out too early -- before the trend gets under way.
I also suggest that you tighten your stops across all positions in a sector if protective stops are triggered on 3 straight trades in that sector (within a reasonable time period). By protective stops I mean a trailing stop designed to exit your position if the trend changes (e.g. a close below a long-term MA). A reasonable time period may vary from a few days for short-term trades to several weeks for long-term trades.
You can limit our market risk in a similar fashion.
Limit your Total Capital at Risk in the market to between 5 and 10 times your (maximum) Capital at Risk per stock (e.g. 10% to 20% of your capital if you are using the 2 percent rule). Adjust this percentage to suit your own risk profile. Also, the shorter your time frame and the higher your Success Rate, the greater the percentage that you can comfortably risk.
It is also advisable to tighten your stops across all positions if protective stops are triggered on 5 straight trades within a reasonable time period. Protective stops do not have to be the original stops set on a trade. You may make an overall profit on the trade, but the stop must indicate a trend change.