ISM Manufacturing PMI

PMI is a diffusion index, and that word explains both its power and its limits. Each respondent answers a simple direction — better, same, or worse — and the index is the share reporting better plus half the share reporting same. That construction puts the neutral line at exactly 50: above it, more firms are improving than deteriorating; below it, the reverse. The crucial consequence is that PMI measures breadth, not magnitude — how many firms are growing, never by how much. A reading of 54 says expansion is widespread, but it cannot tell you whether output rose one percent or ten, which is why PMI signals turning points well but sizes them poorly.

The headline hides the most useful signals. New orders is the most forward-looking subindex, and the spread between new orders and inventories is a classic lead: when orders climb while stockrooms empty, firms will have to lift production soon. Supplier delivery times work in reverse — slower deliveries push the index up because they signal demand outrunning supply, which also makes the component an early inflation gauge, reinforced by the prices paid subindex. And the employment subindex offers a rough preview of what the official payroll report may show. Reading these together extracts far more than the single composite number.

PMI is soft data — it records what managers say, not what factories shipped. That is its great advantage in timeliness, but also its catch: surveys capture sentiment and direction, not dollars, and can be swayed by the mood of the moment or a single dramatic headline. Soft data and hard data (actual production, shipments, orders in dollars) usually move together, but when they diverge — a gloomy PMI beside still-solid output, say — the gap itself becomes the story, and careful analysts treat PMI as a leading hint to be confirmed by the hard numbers rather than as the final word.

Because every PMI is built on the same 50 line, the surveys are unusually comparable across borders, which makes them the premier real-time map of the global cycle — aggregated into the JPMorgan Global PMI that tracks world manufacturing in one series. Timing varies by provider: S&P Global publishes a flash estimate about a week before month-end, based on the bulk of responses, and it frequently moves markets, whereas ISM releases only a final figure. National quirks matter too — China is read through two PMIs, the official NBS survey, tilted toward large state firms, and the private Caixin survey, which leans toward smaller exporters, and the two can tell different stories in the same month.