What Is the Purchasing Managers' Index (PMI)?
What PMI is, why 50 is the line between expansion and contraction, the difference between manufacturing and services surveys, what the sub-indices reveal, and why a timely survey often moves markets more than hard data.
The Purchasing Managers' Index is a monthly survey of the people who buy inputs for businesses. They are asked whether new orders, output, employment, supplier delivery times and inventories are better, the same or worse than last month, and the answers are combined into a single number. Fifty is the dividing line: above it the sector is expanding, below it contracting.
Key Takeaways
- 50 separates expansion from contraction. The distance from 50 indicates breadth, not magnitude.
- Manufacturing and services are surveyed separately. In most developed economies services is the larger sector.
- The sub-indices — new orders, employment, prices paid — often matter more than the headline.
- PMI is timely and forward-looking, which is why it can move markets more than GDP despite being a survey.
How the Number Is Built
Purchasing managers answer a small set of questions about direction, not magnitude. Each answer produces a diffusion index: the share reporting improvement plus half the share reporting no change. A reading of 55 means a clear majority saw improvement; 45 means a clear majority saw deterioration.
This is why the level tells you about breadth rather than size. A move from 52 to 55 means more firms are improving, not that output rose by any particular amount.
| Reading | Interpretation |
| Above 50 and rising | Expansion, broadening |
| Above 50 and falling | Still expanding, losing momentum |
| Below 50 and falling | Contraction, deepening |
| Below 50 and rising | Still contracting, but improving |
The second and fourth rows are where markets often turn, because direction changes before the level crosses 50.
Manufacturing and Services
Both are surveyed. Manufacturing PMI is the more volatile and historically the more watched, partly for its long history and partly because manufacturing turns earlier in a cycle. Services PMI covers the larger share of most developed economies and is the better guide to overall activity. A composite combines them.
Two Providers, Two Series
In the United States, the Institute for Supply Management publishes the long-established ISM surveys, and S&P Global publishes its own PMI series covering the US and most other major economies. They measure similar things with different panels and methods, and they can diverge in a given month. Markets watch both; the ISM series has the longer history and typically the larger reaction in the US.
The Sub-Indices
The headline is a composite, and the components carry information the headline hides:
- New orders — the most forward-looking component; tomorrow's output.
- Employment — a read on hiring intentions ahead of official labour data. See what is nonfarm payrolls.
- Prices paid — an early inflation signal from the input side. See what is inflation.
- Supplier delivery times — lengthening times usually mean demand is outpacing supply.
A headline that holds steady while new orders fall and prices paid rise is a different message from the same headline with the opposite components.
Why It Moves Markets
PMI arrives at the start of the month covering the month just ended, well ahead of hard data on the same period. It is a survey, so it is less precise — and far more timely. Markets pay for timeliness.
The transmission is the usual one: PMI shifts the growth and inflation outlook, which shifts rate expectations, which moves the currency, bond yields and equity valuations. See how interest rates work and why good economic news can cause markets to fall.
Worked Example: The Same Headline, Two Messages
Manufacturing PMI comes in at 51.2 against a 51.0 consensus — in line.
| Case A | Case B | |
| New orders | 53.5, rising | 48.9, falling |
| Prices paid | 52.0, steady | 58.0, rising sharply |
| Reading | Expansion with demand behind it | Output holding on backlog; input costs accelerating |
| Likely reaction | Mild currency support | Currency up on inflation concern, equities down |
The headline was a non-event in both cases. The components were not.
(Illustrative.)
For Traders
PMI is on the economic calendar as medium-to-high impact for the currency concerned, released in the first business days of each month for most economies. Flash estimates for some regions arrive before the final figure and carry most of the market reaction.
What does a PMI of 50 mean?
No change from the previous month. Above 50 indicates expansion, below indicates contraction.
Is manufacturing or services PMI more important?
Services covers the larger share of most developed economies. Manufacturing is more volatile and tends to turn earlier in the cycle.
What is the difference between ISM and S&P Global PMI?
Different providers, panels and methods measuring similar things. Both are watched in the US; ISM has the longer history.
Why does PMI move markets more than GDP?
It is timely and forward-looking. GDP describes a quarter that has ended and is largely anticipated by the time it arrives.
Which sub-index matters most?
New orders as a forward indicator, and prices paid as an early inflation signal.
Related Reading
What is GDP · What is inflation · What is nonfarm payrolls · How interest rates work · How to use an economic calendar
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