Two separate inflation warnings converged this week from very different corners of the market, and together they describe a more troubling picture than either does alone: inflation that is getting harder to dislodge. One comes from physical fuel markets, the other from Fed-adjacent economists — and both point at the same underlying risk from different angles.

The diesel squeeze

The first warning is physical and mechanical. According to Platts, part of S&P Global Commodity Insights, and S&P Global Energy CERA, the Americas are heading into their most diesel-intensive stretch of the year with the thinnest supply buffers seen in recent memory.

Global diesel inventories stood at 542 million barrels as of 21 August, down 28.5 million barrels year over year. Russia and the Middle East, which together account for roughly half of global net diesel length, are both effectively sidelined by sanctions, drone strikes on refining capacity, and Strait of Hormuz disruptions.

US refinery utilisation has hit a record 98%, the USGC ULSD crack spread reached an all-time high of $98.15 a barrel on 1 September, and US inventories sit below the bottom of the five-year range just as fall harvest, early winter heating demand and refinery turnaround season converge on a narrow window. The crack spread — the margin between the price of crude oil and the refined diesel it yields — is a closely watched gauge of distillate scarcity, and a record print means refiners are capturing unusually high margins precisely because supply is stretched.

Diesel is not a niche energy input. It underpins trucking, agriculture, rail and shipping, which means a sustained shortage works its way into the cost of moving and producing nearly everything else in the economy — a cost pressure with a direct mechanical channel into the price of goods. That channel is also unusually hard for policymakers to counter: monetary policy can dampen demand, but it cannot refine more diesel.

Swonk: pipeline inflation is resurging

The second warning concerns how that kind of cost pressure moves through the broader economy, and it comes from KPMG US Chief Economist Diane Swonk, who briefs the Federal Reserve. Writing on X about a meeting of roughly 50 economists across industries and countries this week, held under Chatham House Rules and therefore without individual attribution, Swonk described the picture on inflation that emerged as striking and hot, and consistent with what recent ISM surveys have shown in both the services and manufacturing sectors. The ISM's price indexes capture what purchasing managers report paying for inputs, making them a leading indicator of where consumer-level inflation tends to head when those costs are passed through.

She said the most important signal from ISM price indexes is a resurgence of pipeline inflation pressure rather than further disinflation, with manufacturing reflecting the direct effects of tariffs, imported inputs and supply chain disruption, and services reflecting the broader pass-through of those costs, compounded by labour shortages and wage pressure. Rising transportation and logistics costs, she said, are increasingly spilling from goods prices into services, describing the dynamic as "aftershocks colliding with one another."

Swonk said the tone of discussion at this week's meeting had shifted meaningfully — from whether the Fed needs to hike toward how much tightening it would take to derail a bout of inflation that many industry specialists now see as entrenched, with a growing fear that elevated prices are becoming embedded in firm and consumer expectations even as consumers themselves splinter in how they respond to price increases.

She said the Fed's own Beige Book echoed that rising-pressure narrative while also underscoring a bifurcated, "K-shaped" pattern in consumer spending, in which gains concentrated among less price-sensitive households are enough on their own to keep aggregate spending and inflation elevated — a dynamic she said will not resolve itself if the Fed simply holds rates and waits. The Beige Book, compiled eight times a year from anecdotal reports gathered by the Fed's twelve regional banks, feeds directly into the Federal Open Market Committee's rate-setting discussions, which is what gives the pattern she describes its policy weight.

She pointed to early signs of labour shortages emerging in the Atlanta Fed's wage tracker, with some firming in pay for workers who change jobs even as August ADP data showed only a slight cooling in wages for those who stay in their current roles. She also flagged that benefits costs are poised to accelerate again next year, adding further fuel to services-side inflation.

What the combination means

Neither the diesel story nor Swonk's account of this week's economist discussion is, on its own, proof that inflation is about to break out meaningfully higher. Diesel markets have tightened seasonally before without triggering a broader inflation scare, and Swonk's account draws on an off-the-record meeting whose participants and precise data cannot be independently verified, however credible her own synthesis of public ISM and Beige Book data may be.

It is also worth noting that a portion of current diesel tightness reflects genuinely temporary factors, including Russian export disruption tied to an active conflict and Strait of Hormuz flows that could normalise faster than current forecasts assume, which would ease the cost-pass-through channel described here. What would meaningfully change this picture is a faster-than-expected resolution to Hormuz shipping disruptions, a Russian export recovery, or ISM and CPI data in the coming months showing costs actually being absorbed rather than passed through to consumers.

If the combination does hold, however, the market implications are broad rather than narrow. A genuine risk of more entrenched inflation, layered onto a Fed already debating whether to hike or hold in September, argues for a higher-for-longer rate path than current market pricing reflects. That would typically weigh on equities through higher discount rates and pressure non-yielding assets like gold in the near term, even as gold's traditional role as an inflation and currency-debasement hedge would argue for renewed strength if inflation expectations genuinely become unanchored over a longer horizon.

Those two effects on gold pull in opposite directions depending on the time horizon, which is itself worth watching closely rather than assuming either one dominates. This is a developing risk — not a settled outcome — best reassessed once September CPI data and the Fed's 15 to 16 September decision are in hand, since either could materially shift which of these scenarios is playing out.