Core PCE is the single inflation number the Federal Reserve cares most about when setting interest rates. Running above the 2% target biases the Fed toward tight money (higher rates, brakes on the economy and risk assets); running below biases them toward easy money (lower rates, fuel for both). If you want to anticipate what the Fed will do next — which drives mortgage rates, stock valuations, bond returns, and the dollar — this is the number to watch. It's the link between the inflation data you read about and the rate decisions that move markets.