What Could Crash the Market? The Risks Nobody Prices In
A crash needs two things: a market expensive enough to fall, and a trigger. The crash-risk score watches the first. This section watches the second: the blockade, the tariff, the financing break that arrives from outside the US economy. Every risk here is tracked with live source data.
What external shocks could crash the stock market?
Each risk in this section gets its own page with live data, stated sources and a pre-disruption baseline. If a number cannot be sourced, it is not shown.
Oil Shock
A fifth of the world's oil passes through the Strait of Hormuz and the Bab el-Mandeb. Daily tanker transits from IMF satellite data, against each strait's pre-disruption baseline, alongside the Brent price.
AI Debt
Not all of the AI build-out is paid for in cash. Capex and long-term debt for the biggest builders from their own SEC filings, ranked by debt-to-capex, alongside the CCC-minus-AAA credit spread.
Treasury Dump
Japan is the largest foreign holder of US Treasuries — and those holdings are the ammunition for defending the yen. Monthly TIC holdings against their own peak, alongside the yen and the 10-year yield, with the market-value caveat stated.
Debt Spiral
Interest on the US debt is consuming a rising share of all federal spending, climbing back toward the 1991 record. The quarterly BEA series back to 1947, and the 30-year yield that sets the next decades of interest costs.
What counts as a geopolitical risk to stocks?
These are shocks that start outside the US business cycle and reach US stocks through energy prices, supply chains, financing costs, inflation and interest rates.
Energy chokepoints
A fifth of the world's oil passes through two straits a few miles wide. No pipeline can replace them. When tanker traffic stops, supply stops, and oil prices reset within days. This is the oil shock scenario, tracked live on this site.
Shipping and supply lines
US companies run on just-in-time freight. When a canal, a strait or a port closes, diversions add weeks and war-risk insurance reprices overnight. The extra cost reaches consumer prices before it reaches earnings calls.
Geopolitical conflict
Wars and blockades hit energy, food and insurance markets first. US stocks then reprice the inflation and interest-rate effects within months.
Trade policy
Tariffs and export controls are shocks chosen in Washington and Beijing, not in the US business cycle. They rewrite input costs and supply chains faster than any domestic indicator can drift.
Leverage and financing
A boom built on borrowed money ends when the lending stops. The AI build-out is the live case: hundreds of billions a year in datacentre construction, part of it financed with debt. The credit spread is where a financing break shows up first.
Currency and sovereign debt
The Treasury market sets the price of everything else. Japan, the largest foreign holder, may have to sell Treasuries to defend the yen. At the same time the US interest bill takes a rising share of federal spending. Either one moves the yield that stocks are valued against.
How does an outside shock reach your portfolio?
The chain is short, and it has worked the same way for fifty years.
An outside shock raises the price of something the US economy cannot replace quickly: oil, freight or food. That price feeds inflation within weeks. Inflation moves interest rates, and interest rates reprice stocks. The 1973 embargo, the 1979 Iranian supply cut and the 2022 invasion of Ukraine all followed this chain. You can watch the first link on the live oil shock monitor — tanker transits through Hormuz and Bab el-Mandeb against the Brent price.
Why watch the risks the crash score can't see?
An expensive, late-cycle market absorbs a supply shock much worse than a cheap one.
The crash-risk score measures how expensive and how stressed the market is from the inside: six indicators, scored against fixed thresholds, re-read through the day. It does not say what starts the fall. External risks are the other half: the triggers that turn an expensive market into a falling one. Read the score for how vulnerable the market is, and this section for what could set it off.
Frequently asked questions about market risk
What is geopolitical risk to the stock market?
Geopolitical risk is the chance that events outside the US economy reprice US stocks: wars, blockades, embargoes and trade fights. These shocks follow a set chain. Energy and freight prices move first, then inflation, then interest rates, then earnings and valuations. No domestic indicator warns you about them in advance.
Can an oil shock crash the stock market?
It has before. The 1973 embargo sent oil up several-fold and the S&P 500 lost nearly half its value in the bear market that followed; the 1979 Iranian supply cut doubled crude and forced punishing rate hikes; the 2022 invasion of Ukraine spiked Brent and helped drive the fastest tightening cycle in decades. Not every oil spike causes a crash, but every post-war oil shock has shown up in inflation, rates and stock prices within months.
Why does the Strait of Hormuz matter for oil prices and US stocks?
About a fifth of the world's petroleum liquids consumption passes through the Strait of Hormuz. No pipeline network is large enough to replace it. If traffic stops, the oil does not reroute, and the Brent price moves within days. This site counts the tankers passing through daily, from satellite data, against the pre-disruption baseline.
How do supply chain disruptions affect US equities?
US companies run on just-in-time freight, so a closed canal, strait or port raises input costs across entire sectors at once. Diversions add weeks to voyages, war-risk insurance reprices overnight, and the extra cost shows up in consumer prices before it appears in earnings guidance. Equities then reprice both the margin hit and the tighter rate path the inflation forces.
What is the difference between the crash-risk score and these risks?
The crash-risk score measures the market from the inside: valuation, the yield curve and stress gauges against fixed thresholds. This section watches the outside triggers that can turn an expensive market into a falling one. An expensive, late-cycle market absorbs a supply shock much worse than a cheap one, so the two are read together.
How are these risks tracked on this site?
With live source data, not forecasts. The oil shock page counts daily tanker transits through the Strait of Hormuz and the Bab el-Mandeb from IMF PortWatch satellite data, and pairs them with the Brent price from FRED, each against a stated baseline. If a number cannot be sourced, it is not shown.
Get told when a risk starts moving
One email a week when the score moved, with the chokepoint readings next to the six internal indicators.
At most one email a week, and only in weeks something actually moved. No account, one click to unsubscribe, and the address is never shared.
Explore the Data
Tanker transits through Hormuz and Bab el-Mandeb, against Brent
Who is financing the AI build-out with debt — SEC-filed capex and leverage
Japan's trillion-dollar Treasury holdings, the yen and the 10-year yield
The interest bill on the US debt, against the post-war record share of spending
The internal axis — valuation and stress gauges behind the crash-risk score
The live combined risk assessment
When did the market last look like this — and what followed
Every formula, data source and threshold, stated openly