The Iran war rattled but didn’t break Wall Street this week. Instead it exposed 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. The result was the worst combined week for stocks and bonds since the tariff stress last April, and a market that couldn’t decide whether the bigger threat was inflation or an economic slowdown.
On Friday, the collision sharpened: payrolls unexpectedly fell by 92,000 — one of the largest drops since the pandemic — just as oil topped $90 and a private-credit scare landed, confronting investors with the prospect of a shrinking economy and rising prices in the same breath.
The upshot is clear. The foundational promise of a diversified portfolio — that stocks and bonds move in opposite directions, offsetting losses on one side with gains on the other — misfired in real time. That raises the stakes for investors bracing for a conflict with no clear end.
“War creates no winners. Only relative losers,” said Que Nguyen, chief investment officer at Research Affiliates. “The only place to hide has been energy.”
It was another reminder of the fragility of old-fashioned asset-allocation techniques. While a simpler bonds-stocks mix delivered solid returns in 2025, the strategy has failed just as often in recent years, such as 2022’s bear market. Gavekal Research has gone as far as arguing that bonds have lost their role as a portfolio shock absorber in an era of supply-driven price shocks, proposing that investors replace them entirely with precious metals and energy.
Selling swept across regions and asset classes this week as the geopolitical flareup in the Middle East added fresh stress to markets that are already under pressure from AI disruptions. US bonds dropped the most since last year’s tariffs rout, and the S&P 500 suffered its largest weekly loss since October. Emerging-market equities slid more, posting their biggest slump since 2020.
Making things worse: just like Treasury bonds, assets long perceived as haven assets — gold, shares of consumer-staples makers — ranked among the worst performers.
Funds that are designed to weather shocks, such as trend following and risk parity, got hit. The RPAR Risk Parity ETF, for instance, slipped more almost 4%, its worst return in more than three years.
To Jack Janasiewicz, portfolio manager at Natixis Investment Managers, the rout reflects growing fear over stagflation, a scenario where higher energy costs revive inflation and eat into consumer wallets, slowing economic growth. He recently raised cash, trimming holdings in emerging markets and US cyclical stocks.
“There’s a risk here going forward of this being a protracted issue and it all comes back to that oil price,” he said. “You’ve got a little bit of potential for repricing inflation expectations, but at the same time you got to think about the demand destruction.”
While almost everything fell together, the extent to which assets moved varied drastically, worsening market dislocations. Ranking assets by their volatility relative to their own history, Barclays strategists including Stefano Pascale found that the stress gap between the top and bottom asset has never been this wide in data going back to 2010.
For investors, the immediate question is whether the stress stays quarantined in commodities or migrates to other assets. Barclays notes that divergences of this magnitude have historically resolved in one direction or the other — but never held.
The S&P 500 still sits within 3% of an all-time high reached in January, while 10-year Treasury yields hovered near the lowest since 2024. If oil remains above $90 and the Strait of Hormuz stays effectively shut, the inflation channel will keep grinding against the rate-cut hopes that Friday’s jobs report briefly revived.
Spreading bets widely is far from a no-brainer. US equities have proved stubbornly resilient, with dip-buyers stepping in after every selloff this week, and the cost of rotating into defensive positions — missing a snapback rally, locking in low yields, paying for options protection — remains steep in a market still near record highs. But for those unwilling to bet on a quick resolution, options exist: long energy, short duration, commodity-linked notes, quant tactics and tail-risk strategies designed to pay off only when everything else fails.
Signs of angst are creeping up. The Cboe Volatility Index, a gauge of implied price swings in the S&P 500 known as the VIX, surged toward 30, pushing the spot price above its three-month futures in the largest inversion in almost a year.
In the credit market, the premium investors demand for owning investment-grade bonds over Treasuries widened to a three-month high. Meanwhile, hedge funds have slashed their net exposure to levels not seen since 2022, according to data compiled by PivotalPath.
The AI spending wobble that dragged software stocks lower before the war began has not gone away — it has simply been overshadowed. The risk is that investors are still positioned for a repeat of past downturns — a world where bonds still hedge and inflation is still transitory — while the market is telling them neither assumption holds.
Patrick Brenner, chief investment officer of multi-asset at Schroder Investment Management, said his team has been favoring real assets such as commodities.
“Diversification is not simply about holding different assets, but about holding assets that respond differently under pressure,” he wrote in a note with colleague Joven Lee.
Written by: Lu Wang (News) — With assistance from Mia Gindis @Bloomberg
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