CPI (Consumer Price Index)
The headline measure of how much prices have risen, based on a basket of goods and services consumers buy — the core yardstick for measuring inflation.
CPI = the prices of a representative basket of consumer items (food, housing, transportation, etc.) turned into an index
When the CPI growth rate runs above the Fed's target (usually 2%), it is read as pressure toward tightening (rate hikes); when it falls, expectations for easing grow.
In plain terms
CPI puts the goods and services we buy day to day (food, rent, transportation, medical care, etc.) into one basket and measures how much their prices have risen compared with last year. It is the most representative ruler for measuring inflation (rising prices).
It is released monthly by the U.S. Department of Labor and is one of the economic figures the market watches most closely. When CPI comes in higher than expected, the market reacts with "prices aren't cooling → the Fed may raise rates further," and stocks swing.
What it tells you
CPI is the number the Fed weighs most heavily when setting interest rates. So a CPI release is a hint about "where rates are headed," and it can move the whole market regardless of any individual company's results.
Core CPI, which strips out volatile energy and food, is looked at alongside it. The idea is to remove temporary swings and see the underlying trend in prices.
Formula
CPI = the prices of a representative basket of consumer items (food, housing, transportation, etc.) turned into an index CPI growth (YoY) = the rise in prices versus the same month a year ago = the inflation rate
What high or low means
When the CPI growth rate runs above the Fed's target (usually 2%), it is read as pressure toward tightening (rate hikes); when it falls, expectations for easing grow.
The market has already priced in the CPI it expects, so big moves come when the release deviates from expectations. That means the same figure can draw different reactions depending on how far it lands from forecasts.
CPI is based on an "average shopping basket," so it can differ from the prices any one person feels. Someone buying a home versus someone renting, someone who drives versus someone who doesn't — each experiences it differently.
Looking only at headline CPI (the overall figure) leaves you swayed by swings in energy and food. Core CPI gives a more accurate read on the trend.
CPI is a macro indicator, so the market's reaction doesn't always follow the textbook. Think of this term as background knowledge for making sense of market news. (※ Our screens deal with individual companies' SEC-filed financials and don't provide macro indicators like CPI themselves.)
In 2022, U.S. inflation (CPI) surged to 9.1% year over year in June, the highest in roughly 40 years. On each CPI release day, the fear that "inflation came in higher than expected → the Fed will raise interest rates further" sent stocks swinging sharply.
The Fed did in fact lift its policy rate rapidly that year, from near 0% to the 4% range, and U.S. stocks fell into a bear market over the course of 2022. It was a year that vividly showed how a single macro indicator like CPI can move the whole market, regardless of individual companies' results.
Metrics to read alongside
See it in real stocks
Search US stocks on Stocklore to see SEC-filing-based financial metrics alongside the sector benchmark.
This explanation is for information and reference only and is not a recommendation to buy or sell any security. Investment decisions and their consequences are your own.