Goldman estimates the six‑month realized correlation among S&P 500 constituents has dropped to 11 — the lowest in about 25 years, with comparable readings only in Feb 2007 and Jan 2018. Low correlation reflects idiosyncratic stock moves tied to AI, earnings and sector dynamics that offset one another and suppress index realized volatility; Goldman cautions that a macro shock that re-synchronizes stock moves could rapidly amplify index volatility as diversification wanes. Cboe notes correlation s

Goldman estimates the six‑month realized correlation among S&P 500 constituents has dropped to 11 — the lowest in about 25 years, with comparable readings only in Feb 2007 and Jan 2018. Low correlation reflects idiosyncratic stock moves tied to AI, earnings and sector dynamics that offset one another and suppress index realized volatility; Goldman cautions that a macro shock that re-synchronizes stock moves could rapidly amplify index volatility as diversification wanes. Cboe notes correlation spikes typically coincide with higher systemic risk and tail volatility: in March 2026 one‑month implied correlation rose from roughly 15 to 40, quickly pressuring dispersion trades.