Correlation Risk: When Five Trades Are Really One

You follow the 1% rule on every trade. You have five positions open. If the market drops sharply, you could lose 5% in one move, because the five positions are not five independent bets. They are one bet, five times. That is correlation risk.

What correlation means

Correlation measures how closely two instruments move together, from −1 (opposite) through 0 (unrelated) to +1 (in lockstep). Many instruments traders hold together are strongly positively correlated:

• Stocks in the same sector, such as several semiconductor stocks.
• Most large stocks during a broad market selloff.
• Currency pairs sharing a currency, such as EUR/USD and GBP/USD, which often move together against the dollar.
• Most cryptocurrencies, which often move with Bitcoin.
• Index futures and the stocks that make up the index.

Why it matters

When positions are correlated, their losses arrive together. Your planned 1% risk per trade becomes 3% or 5% per market move. Correlations also tend to rise in sharp selloffs, so diversification often disappears exactly when you need it.

How to manage it

1. Count exposure by theme, not by ticker. Three chip stocks long is one large semiconductor position.
2. Set a limit per theme, for example 2% total risk across all positions in one sector or one currency.
3. Reduce size on additional correlated trades. The second trade in a theme gets half size, the third is skipped.
4. Watch the market factor. In stocks, most longs share exposure to the overall market. A short index hedge can reduce it.
5. Check currency exposure in forex. Long EUR/USD and long GBP/USD are both short the US dollar.

Correlation and your journal

Look at your worst days. Were they days with many positions in the same direction or theme? If so, your maximum drawdown is being driven by correlation, not by individual trades. Tag trades by sector or theme to see your exposure clearly.

In TradeThink

The open positions page lists all open positions with filters by asset class, side and more, so you can see how much of your risk is pointing the same way. Use tags for sectors or themes and check results by tag in the reports. Related: leverage and margin.