The Purchasing Managers’ Index (PMI) is a survey-based indicator designed to show whether business activity is improving or weakening. A reading above 50 generally signals expansion from the previous month, while a reading below 50 generally signals contraction.
How it works
PMI surveys ask businesses about areas such as output, new orders, employment, supplier deliveries, and inventories. The responses are converted into diffusion indexes that summarize whether conditions are improving, unchanged, or worsening.
Manufacturing and services PMIs can tell different stories because the two sectors respond differently to trade, interest rates, consumer demand, and supply conditions. The direction and distance from 50 are often as important as the headline level.
Why it matters
PMIs are usually published earlier than many official growth statistics, so investors use them as timely clues about economic momentum. A sharp move can influence earnings expectations, bond yields, and policy expectations.
A sub-50 PMI does not mechanically mean stocks should fall. Markets may already expect weakness, or investors may focus on the possibility of policy support.
A simple market example
If manufacturing PMI falls from 50.3 to 49.2, the survey has moved from slight expansion to slight contraction. The market impact still depends on whether investors expected an even weaker result and what the data imply for policy and profits.
Common mistakes
Calling 49.9 a 49.9% contraction. PMI is an index, not a percentage change in output.
Treating 50 as a cliff. A small move around 50 can reflect modest changes, while a large move can signal a much stronger shift in momentum.
Frequently asked questions
Why is 50 important in PMI?
Because 50 is the neutral threshold: above it more respondents report improvement than deterioration, while below it the balance is negative.
Is PMI the same as GDP?
No. PMI is a survey indicator of business conditions; GDP is an official measure of economic output.
Which matters more, manufacturing or services PMI?
It depends on the economy. Services often make up a larger share of developed economies, while manufacturing can be especially important for trade-sensitive markets.
Educational content only. Definitions describe common market usage and may vary by jurisdiction, instrument, or institution.