The Iran war rattled but didn't break Wall Street this week, exposing the limits of diversification strategies built to cushion investors against chaos. Throughout the week, stocks and bonds repeatedly fell together as oil surged and the inflationary shock of a supply disruption pushed Treasury yields higher instead of lower — the opposite of the crisis playbook.

This created the worst combined week for stocks and bonds since the tariff stress last April, leaving markets unable to decide whether the bigger threat was inflation or an economic slowdown. The foundational promise of a diversified portfolio — that stocks and bonds move in opposite directions, offsetting losses — misfired in real time. The S&P 500 suffered its largest weekly loss since October, while US bonds dropped the most since last year's tariffs rout.

Funds designed to weather shocks, such as trend following and risk parity, got hit hard. The RPAR Risk Parity ETF slipped almost 4%, its worst return in more than three years. With the Cboe Volatility Index surging toward 30 and hedge funds slashing net exposure to levels not seen since 2022, investors face a market where traditional haven assets failed and the inflation channel grinds against rate-cut hopes.