PMI (Purchasing Managers' Index)

The Purchasing Managers' Index (PMI) is a leading economic indicator derived from monthly surveys of private sector companies. A PMI above 50 represents expansion; below 50 represents contraction.

PMI is a leading economic indicator — it tells you what's happening in the economy before official GDP data is published. A falling PMI alongside rising CPI signals stagflation — the most damaging macro condition for equity valuations.

Further reading: Wikipedia