Oil near $100 a barrel, diesel at a record $6.40, and Gulf shipping flows that have recovered in volume but not in price. Energy and supply risk used to be a footnote in macro models. In 2026 it is setting headline inflation, shaping Fed decisions and moving household sentiment.
This is the third of four letters published together in October 2026. Macro models have long treated energy and supply-chain risk as a footnote — an occasional shock that fades. In 2026 that assumption failed. The disruption around the Strait of Hormuz is setting headline inflation, constraining the Fed, and pressing on household sentiment. The surprising part is what the physical data now say: the barrels have mostly come back. The price has not.
A Dallas Fed working paper describes the closure of the Strait of Hormuz as "the largest geopolitical oil supply disruption in history," removing roughly 20% of global supply — two to three times larger than the 1973 and 1990 disruptions. It estimated that, depending on how long the closure lasted, fourth-quarter-over-fourth-quarter headline PCE inflation in 2026 could rise by 0.2 to 1.8 percentage points, against only 0.1 to 0.5 points for core inflation. That asymmetry shows up in the data: August headline CPI was 3.4% while core was 2.4%, with the energy index up 16.3% and gasoline up 27.4% over twelve months.
But the physical picture has changed. Kpler data cited by Oilprice.com show crude flows through the Strait of 19.5 to 22.5 million barrels a day between September 27 and 29 — above the roughly 18 million barrels a day pre-war average and about double the level a month earlier. About 40% of Middle Eastern crude now bypasses the Strait through alternative routes. And still Brent traded near $101.6 a barrel on October 5 and WTI near $90, after oil rose 13.7% in September alone, with strategic reserve releases providing only marginal relief.
| Indicator | Latest | Context |
|---|---|---|
| Brent crude (Oct. 5) | ~$101.6 | Still far above pre-war levels |
| WTI crude (Oct. 5) | ~$90.05 | Marginal declines after reserve releases |
| Hormuz crude flows (Sept. 27–29) | 19.5–22.5M bpd | Above ~18M pre-war average (Kpler) |
| Oil price change in September | +13.7% | Despite recovering volumes |
| US gasoline (Sept.) | $4.44 | CPI gasoline +27.4% YoY (Aug.) |
| US diesel (Sept.) | $6.40 | Record high; $3.71 a year earlier |
When flows recover and prices do not, the market is paying for something other than barrels. Analysts quoted by Al Jazeera debate what: elevated insurance costs from continued attacks on shipping and regional infrastructure (including reported Houthi strikes on Saudi targets), logistics disruption, and a possible informal toll for safe passage — which a Kpler analyst suspects but which remains unverified. This letter's reading is that the market is pricing uncertainty rather than scarcity: a risk premium for the possibility that flows can be interrupted again, which does not fall until the interruption risk does.
The macro chain from there is short. Higher energy costs lift headline inflation, which keeps the Fed from looking through the shock. A Fed that cannot ease holds borrowing costs near 7% for mortgages. Households facing $4.44 gasoline and 7.28% mortgages report depressed sentiment — the Michigan index's year-ahead inflation expectations rose from 3.4% before the conflict to 4.6%. One regional supply risk therefore runs straight through the rates, housing and consumer-confidence stories of Letters 201 and 202.
The interpretation that a risk premium — not a physical shortage — is holding prices up is a judgment. The same facts are also consistent with transit costs and insurance repricing that persist for structural reasons, or with data that lag the physical reality. The toll claim is explicitly unverified. And the other direction is just as plausible: if a durable settlement lowers interruption risk, oil could fall sharply, because the barrels are already flowing. This letter is not forecasting a price; it is arguing that the risk should no longer be modelled as background noise.
A shock that has stopped being a shortage and started being a premium is harder to price, because it ends when confidence returns, not when supply does.
The central risk to this letter is a settlement. If Gulf shipping risk falls decisively, the premium unwinds, energy-heavy positions lose their tailwind, and the headline-versus-core gap in inflation narrows quickly, which would also change the Fed's calculus. The opposite risk is escalation: recent reports of attacks on Saudi infrastructure show the interruption risk has not gone away. Both outcomes are binary events that no macro model prices well, which is the point of treating geopolitics as a driver rather than noise.
Energy and supply risk are no longer background. They set headline inflation, constrain monetary policy and shape household sentiment — and in 2026 they did so even as physical flows recovered. The practical stance is to hold some exposure that benefits if the premium persists, size positions that suffer from high energy costs for a regime in which the price does not fall just because the ships are moving, and keep a plan for the day a settlement removes the premium all at once.