The stock-bond correlation has flipped from positive to negative, according to new San Francisco Fed research, signaling a shift from demand-side to supply-side economic risk.
The stock-oil correlation changed sign around the same time, reinforcing the interpretation that markets now price oil prices and inflation as leading threats.
Researchers cite the 2020s’ string of supply shocks — COVID-19, geopolitical energy disruptions, AI-driven shifts, immigration changes, and tariffs — as the backdrop for this structural change.
Here’s a chart pattern that matters more than most headlines: the correlation between stocks and bonds has quietly flipped, and it’s telling investors something important about what they should actually be afraid of. In a new Economic Letter published August 10, 2026, San Francisco Fed researchers Thomas Mertens and Wesley Wasserburger document that this correlation — long positive during the 2000s and 2010s — has turned negative in recent years, a shift already observed in market data rather than a future prediction.
From Demand Fears to Supply Shocks
The logic is straightforward: when demand drives the economy, stronger growth lifts both stock valuations and bond yields (via inflation), producing a positive correlation. When supply constraints dominate instead, weaker output hurts stocks while inflation still pushes yields up, flipping the relationship negative. The researchers find the stock-oil correlation moved in tandem, and that uncertainty around oil prices now coincides with higher equity valuations — evidence, they argue, of a structural shift in how markets perceive risk. They point to a decade’s worth of supply disruptions: the COVID-19 pandemic’s dual demand-and-supply shock, energy price spikes tied to conflicts in Europe and the Middle East, AI-driven shifts in production, changing immigration patterns, and expanded tariff policies.
What This Means for Your Portfolio and Wallet
If markets are now pricing supply shocks as the dominant risk, that has real implications for portfolio construction: traditional stock-bond diversification, which relies on the two assets moving in opposite directions during downturns, may behave differently than investors have grown used to over the past two decades. That could mean bonds offer less of a cushion during an oil-driven equity selloff than history suggests.
Strategic Positioning & Defense Ideas
Given this shift, investors might consider broadening diversification beyond the classic 60/40 stock-bond split — adding commodities, energy equities, or inflation-linked assets that can perform differently under supply-driven inflation scenarios. Disclaimer: This analysis is for educational and informational purposes only and should not be construed as financial or investment advice.
What to Watch Next
Watch for how the stock-bond correlation behaves during the next major volatility event, and whether oil price swings continue to coincide with equity valuation shifts. Full details via the Federal Reserve Bank of San Francisco.
