Core Inflation

Core inflation is inflation with the most volatile prices removed, in practice food and energy. The point is signal over noise: petrol prices can jump 10% on an oil headline and fall back a month later without telling you anything about the underlying economy. Central banks set interest rates against the trend, so core is the number they, and therefore currency markets, care about most.

Headline vs core

Headline inflation is what households actually pay, so it dominates news coverage and inflation expectations. Core is what policy responds to. Both versions exist for the major gauges: CPI and, in the US, PCE, whose core version is the Federal Reserve's target measure. Within core, analysts go one layer deeper into services inflation, which tends to be sticky and wage-driven, the slowest part of inflation to come down once it settles in.

A worked example

Suppose US CPI prints: headline 2.9% year on year against 3.1% expected, but core 3.4% against 3.2% expected. The dovish headline says inflation is cooling; the hot core says the cooling came from cheaper petrol while underlying pressure firmed. Markets trade the core: expected rate cuts get pushed back, and the dollar strengthens on a report that a casual reader would call soft. Divergences like this are among the most common ways inflation days wrong-foot traders who only watch the headline.

The mistake to avoid

Do not average the two numbers into one impression. Decide in advance which one the central bank is anchored to right now, and let that number set your read. When a bank has explicitly said it watches core services inflation, a hot headline built on energy is close to irrelevant, and trading it as hawkish is fighting the bank's own reaction function.