Home › FX Trading School › Pro

Portfolio Heat & Correlated Risk: A Pro Trader's Guide

Pro Updated 14 July 2026 · 8 min read · PipTax education

Portfolio heat is the total amount of capital you have genuinely at risk across every open position at once — and for most retail traders, it's badly underestimated because they only ever look at risk one trade at a time. This lesson builds directly on the position-sizing and per-trade risk rules covered earlier in the course, and extends them to the whole portfolio, where correlated pairs can quietly stack risk you never intended to take.

What Portfolio Heat Actually Measures

Per-trade risk answers "how much do I lose if this one stop is hit?" Portfolio heat answers a bigger question: "how much do I lose if several of my open trades go wrong together?" That second question matters because currency pairs rarely move in isolation.

To calculate portfolio heat properly you need:

• Every open position's risk in account currency (distance to stop × position size)
• The correlation between each pair of open positions
• A combined "effective risk" figure, not just a simple sum

If you have three uncorrelated 1% trades, your heat is roughly 3%. If you have three trades on pairs that move together, your effective heat could behave more like a single 3% (or larger) trade — because one market event can hit all three stops at once.

This is the core professional skill this module teaches: separating nominal risk (what your position sizing calculator says) from effective risk (what actually happens to your equity when markets move).

Why Correlated Pairs Multiply Risk

EUR/USD, GBP/USD, and AUD/USD all tend to move against the US dollar to varying degrees. A trader who opens long positions in all three, each sized at 1% risk, might believe they're running 3% total risk. In practice, if the move is driven by broad USD strength or weakness, all three trades win or lose together — meaning the real risk exposure to "USD direction" is closer to 3% concentrated in one bet, not three diversified ones.

Common correlated clusters worth knowing:

• USD majors: EUR/USD, GBP/USD, AUD/USD, NZD/USD often move together against USD strength/weakness
• JPY crosses: USD/JPY, EUR/JPY, GBP/JPY often share yen-driven risk sentiment moves
• Commodity-linked: AUD, NZD, CAD often correlate with commodity prices and risk appetite
• Gold and USD: XAU/USD frequently moves inversely to broad dollar strength

None of these correlations are fixed. They shift with central bank policy divergence, risk-on/risk-off cycles, and unexpected news — which is exactly why heat needs checking regularly, not set once and forgotten.

Building a Simple Correlation Matrix

You don't need institutional software for this. A basic correlation matrix is enough to catch the majority of dangerous overlaps.

Steps:

1. Pull daily closing prices for the pairs you commonly trade (30-60 days is a reasonable window) 2. Calculate the Pearson correlation coefficient between each pair (a simple spreadsheet formula) 3. Build a grid: anything above +0.7 or below -0.7 is a strong correlation worth respecting 4. Re-run this check weekly, and immediately after major central bank events

Reading the matrix:

| Correlation range | What it means | |---|---| | +0.7 to +1.0 | Pairs move together — treat combined positions as one large bet | | -0.7 to -1.0 | Pairs move opposite — a long/long or short/short combo can offset naturally | | -0.3 to +0.3 | Broadly independent — genuine diversification |

This matrix becomes a permanent part of your pre-trade checklist, sitting alongside your position sizing rules.

Setting a Portfolio Heat Ceiling

Once you can see correlated clusters, set two limits rather than one:

• Per-trade risk cap — commonly 0.5-2% of equity, as covered in earlier position-sizing lessons
• Total portfolio heat cap — commonly 5-8% of equity across all open positions, adjusted down further for correlated clusters

A practical rule many professional desks use: if two or more open positions have a correlation above 0.7, treat their combined risk as a single position for the purposes of your heat ceiling — not the sum of two separate allowances.

Worked example:

• Trade A: EUR/USD long, 1% risk
• Trade B: GBP/USD long, 1% risk
• Correlation between the two: 0.82

Effective heat from this cluster ≈ 1.5-2% (not 2%, but not 1% either — somewhere in between depending on how tightly they move together), so you'd have less room left for a third uncorrelated trade before hitting your 5-8% ceiling.

Adjusting Position Size for Correlation

Once you've identified a correlated cluster, you have three practical levers:

• Reduce size on the second and third correlated trade — if you're already long EUR/USD, size a new GBP/USD long smaller than you would if it were your only position
• Skip the trade entirely if your heat ceiling is already close to being hit
• Diversify into a genuinely uncorrelated instrument instead, if the setup quality is similar

This is also where broker mechanics matter. Margin requirements, swap rates, and even execution differences between a MetaTrader environment — such as Pepperstone's MT4/MT5 servers — and a proprietary platform like IG's own dealing platform can affect how "expensive" it is to hold multiple correlated positions overnight. Swap costs on three correlated pairs held long-term can add up differently depending on the broker, so it's worth checking real numbers on the cost tool at /audit.html and comparing broker-specific conditions on /brokers/index.html before assuming position sizing is your only cost consideration.

Common Mistakes That Inflate Portfolio Heat

Watch for these recurring errors:

• Treating "different pair" as "different risk" — GBP/JPY and EUR/JPY can share more risk than the ticker symbols suggest
• Ignoring correlation shifts — a pair correlated at 0.3 last month can jump to 0.8 after a policy surprise
• Forgetting non-FX instruments — gold, indices, and even crypto CFDs can correlate with your FX book
• Only checking heat at trade entry — heat changes as trades move into profit or loss and as new positions open
• Confusing hedging with heat reduction — opposite positions in correlated pairs cut directional risk but add spread and swap cost on both legs, which is rarely efficient for retail-sized accounts

Building a habit of checking your correlation matrix and recalculating total heat before every new trade is the single biggest upgrade a discretionary trader can make at this stage of the course.

Conclusion: Make Portfolio Heat Part of Every Trade Decision

Portfolio heat is what separates traders who think they're diversified from those who actually are. Checking correlation before adding a new position, capping total heat rather than just per-trade risk, and re-running your matrix regularly won't guarantee profits — nothing does, and most retail accounts still lose money even with good risk controls. But it will stop a single market driver from doing far more damage to your account than your position sizing rules ever intended. Pair this discipline with real cost data from /audit.html and broker comparisons at /brokers/index.html, and revisit /school/index.html for the earlier modules this lesson builds on.

Keep going: Audit Cost Impact Index Index