US inflation lands in eighty minutes — and only one of the two numbers matters.

The setup

What lands. US consumer prices for September, at 12:30 UTC — the last inflation reading before the Federal Reserve decides on 28 October.

What's expected. Headline inflation to jump to around 3.6–3.7%, from 3.4%. Core inflation, which strips out food and energy, to sit near 2.4–2.5%, barely moved.

What's at stake. The Fed is at 3.75–4.00% after raising in September. October is priced at only around 20–25%. A rise by December is largely priced.

Why it's live. The headline jump is energy, and the Fed has said it looks through that. The question is whether the energy shock has leaked into core.

The forecast

Headline, monthly +0.6% against +0.4% previous. Headline, yearly 3.6–3.7% against 3.4%. Core, monthly +0.2% against +0.3%. Core, yearly 2.4–2.5% against 2.4%.

Monthly figures and core from Newsquawk's consensus; the yearly range reflects a spread between street consensus at 3.7% and the Cleveland Fed nowcast at 3.60%.

Why it matters

Headline inflation at 3.7% will lead every news bulletin and it is the number that matters least. Petrol and energy are doing it, the Fed has said repeatedly that it looks through base effects in the headline, and nothing in a high headline alone changes a rate decision.

Core monthly is the number. It came in at +0.3% in August — the fastest monthly pace in four months. Consensus has it slowing back to +0.2%. If it does not slow, that is two consecutive months of prices broadening beyond energy, and the argument that this is "just an oil shock" stops working.

That is the whole report in one line: has the energy shock reached everything else, or hasn't it.

If it comes in hot

Core monthly at +0.3% or above revives October. With only about a fifth to a quarter of a rise priced for the 28th, there is a great deal of room for that number to climb. Short-dated yields would move first, then the dollar.

If it comes in soft

Core monthly at +0.1% or below confirms the energy story is contained. October goes quiet, attention moves to December — and with hiring having stalled, a soft core print would start to put even December in question. The dollar softens.

The lean

The risk is asymmetric, and it points hawkish. Not because a hot print is more likely — the forecasters broadly expect core to cool — but because of what is priced. October sits at around 20–25%. A soft number mostly confirms what the market already believes and has limited room to move it. A hot number has to be built in from close to nothing.

Put plainly: the downside surprise is largely in the price, the upside surprise is not.

Ideas

No position into the print. The surprise is unknowable and the first candles after a release are noise in both directions. The trade is the repricing afterwards, not the number.

What to be ready for. A hot core print is the cleaner of the two to act on, because it moves a figure that has barely any expectation built into it. A soft print confirms consensus and will be a slower, smaller move.

Then check the follow-ups. Producer prices land tomorrow and Chair Warsh speaks on Friday. Either can confirm or undo whatever this print does.

Sources

Newsquawk — CPI primer, consensus and Fed pricing · Admiral Markets — scenarios, thresholds, nowcasts, Fed odds history · ForexFactory — preview, energy versus core framing