The 60/40 Problem Returns

GMO argues the traditional stock-and-bond portfolio is becoming structurally less reliable as inflation shocks, geopolitical conflict, and positive stock-bond correlations erode diversification. 

• In March 2026, a traditional 60/40 portfolio lost roughly 5% in a single month during the Iran energy shock.
• GMO warns that equities and bonds are increasingly exposed to the same macro risks, including inflation, AI disruption, and stagflation.
• The firm argues many private-market strategies only appear diversified due to illiquidity and appraisal smoothing, not fundamentally different return drivers.
• GMO’s liquid alternatives strategy targets cash +4% returns with low correlation through macro, trend-following, volatility, and arbitrage strategies.

The deeper argument is not simply about hedge funds. It is about the growing scarcity of true diversification in a world where traditional assets increasingly move together.