The Consumer Price Index measures the monthly change in prices paid by urban consumers for a representative basket of goods and services — housing, food, transportation, healthcare, apparel and recreation. It is the most widely cited inflation measure and directly affects Social Security adjustments, wage contracts and Treasury Inflation-Protected Securities payouts. The headline CPI includes all components; core CPI excludes food and energy, which are volatile but also the components most directly felt by households in their daily expenses. Shelter — primarily imputed rent for homeowners and actual rent for renters — carries the largest weight in CPI and is notoriously slow-moving, which means CPI can reflect past housing market conditions for a year or more after the actual market has changed. The Fed officially targets PCE (Personal Consumption Expenditures) inflation, not CPI, but CPI is the more followed public measure. When CPI prints above expectations, bond yields typically rise and equity valuations face pressure; when it comes in below expectations, the opposite typically occurs. For investors, tracking the trend in CPI — and specifically whether services inflation is decelerating — is the most important input to anticipating the pace and direction of Federal Reserve policy changes.
