Market Correlations: How Stocks, Forex, and Commodities Move Together

Correlation describes how closely two instruments tend to move in relation to each other. A positive correlation means they tend to move in the same direction; a negative correlation means they tend to move in opposite directions; no correlation means their movements are essentially unrelated. Correlations aren't fixed laws — they shift over time as the underlying economic relationships change — but persistent patterns do show up often enough to be useful context.

The US dollar sits at the center of many well-known cross-asset correlations, since it's the currency most commodities are priced in globally. Gold has historically shown a negative correlation with the US dollar — when the dollar weakens, gold (priced in dollars) often becomes cheaper for holders of other currencies, which can increase demand and push its price up, and vice versa. Oil shows a similar, though less consistent, negative relationship with the dollar for the same underlying reason.

Currency pairs that include commodity-exporting countries' currencies — the Australian dollar (tied to metals and mining exports), the Canadian dollar (tied to oil exports) — often show positive correlation with the commodities their economies depend on. When oil prices rise, the Canadian dollar has historically tended to strengthen, since Canada's export revenue is meaningfully tied to oil.

Stock indices and currencies also interact, though the relationship is more nuanced — a weaker home currency can boost a stock index composed of exporters, since their overseas revenue becomes worth more when converted back, while the same weak currency can hurt an index composed of import-dependent companies. Being aware of these relationships helps in two practical ways: recognizing when a move in one market might be a leading signal for another, and avoiding accidentally taking two correlated positions that are really just one large bet in disguise.