What is the Purchasing Managers' Index (PMI)

Discover the PMI and How It Helps Investors

Investors use PMI surveys as leading indicators of economic health
Investors use PMI surveys as leading indicators of economic health. Getty Images/KTSDESIGN

Most economic indicators look at historical data to draw conclusions, but economic surveys offer a glimpse into the future, making them especially valuable to investors.

The Purchasing Managers' Index (PMI) is an economic indicator that surveys purchasing managers at businesses that make up a given sector. The most common PMI surveys are the manufacturing PMI and the services PMI, which are released for the United States and many other developed countries around the world, including members of the eurozone.

Investors use PMI surveys as leading indicators of economic health, given their insight into sales, employment, inventory and pricing. After all, manufacturing purchasing trends reacting to consumer demand are the first visible sign of a slowdown. They are also among the most highly watched economic indicators since they are often the first major survey released each month.

In this article, we will take a look at how the Purchasing Managers' Index is calculated, how to interpret the results of the surveys, and other important considerations for investors.

Calculating the Purchasing Managers' Index

The Purchasing Managers' Index consists of several different surveys that are compiled into a single numerical result depending on one of several possible answers to each question. The exact questions and answers on the surveys vary based on the surveyor, with the two most common surveyors being the Institute of Supply Management (ISM) and Markit Group.

The most common elements included are:

  • New Orders
  • Factory Output
  • Employment
  • Suppliers' Delivery Times
  • Stocks of Purchases

And, the most common answers are:

  • Improvement
  • No Change
  • Deterioration

The actual formula used to calculate the PMI assigns weights to each common element and then multiplies them by 1.0 for improvement, 0.5 for no change, and 0 for deterioration.

A reading above 50.0 suggests an improvement, while a reading below 50.0 suggests deterioration. The groups also divide the survey into the manufacturing and services sectors since manufacturing is export-dependent and services is more sensitive to the domestic economy.

The Purchasing Managers' Index and Investors

The Purchasing Managers' Index is an extremely important indicator for international investors looking to form an opinion on economic growth. In particular, many investors use the PMI as a leading indicator for Gross Domestic Product (GDP) growth or decline. Central banks also use the results of PMI surveys when formulating monetary policy, which can be clearly seen in the Federal Reserve's minutes.

When it comes to predicting GDP growth, a sustained reading of higher than 42.0 is considered to be the benchmark for economic expansion. Meanwhile, a sustained reading of below 42.0 could indicate that an economy is heading into a recession. The difference between 42.0 and 50.0 can indicate the strength of an economic recovery.

Individual components of the PMI can also be useful in various markets. For instance, the bond markets watch growth in supplier deliveries and prices paid, since these figures can provide insight into the potential for inflation.

Since bonds are fixed income assets, inflation has a detrimental effect that can erode their prices.

Finding Purchasing Managers' Index Data

The Purchasing Managers' Index is published in a variety of different places, depending on the company and country. For instance, both Markit and ISM publish PMI data for the United States, while China's Bureau of Statistics provides its own set of figures. In general, most investors trust the two most popular sources - ISM and Markit - for PMI data.

Here is a link to one of these popular sources:

Key Takeaway Points

  • The Purchasing Managers' Index (PMI) is an economic indicator that surveys purchasing mangers at businesses that make up a given sector.
  • Investors use PMI surveys as leading indicators of economic health, given their insight into sales, employment, inventory and pricing.
  • Generally, a prolonged reading above 42.0 is considered to be the benchmark for economic expansion, while a reading below could indicate a coming recession.
  • Individual components of the PMI can be very useful in predicting things like inflation.