Correlation Risk on Prop Accounts: When Three Trades Are Really One

[FXS Prop Desk]

Opening EURUSD long, GBPUSD long and AUDUSD long at the same time looks like three trades. In practice, it is mostly one trade: short USD.

It is also worth remembering that correlation increases in stressed markets. Pairs that seem only moderately related on a quiet week can move almost identically after a surprising US release, which is precisely when stops cluster.

Why this matters with drawdown limits:

• If each trade risks 0.5%, a USD move against you can hit all three, effectively risking 1.5%.
• On news days, correlations go close to 1 for a few minutes.

Practical approaches:

• Count USD exposure in total, not per pair.
• Limit combined risk per currency (e.g. 1% max on USD direction).
• Use correlation tables for the last 20–60 days as a guide, not as a fixed number.

Do you cap your total exposure per currency, and how do you track it during the day?