What Is Inflation? CPI vs PPI, Explained
You’ve heard the words: CPI, PPI, core, hot print, sticky inflation. Markets lurch violently when these reports land, and the commentary insists the Fed is either winning or losing depending on the day. But strip away the jargon and there are really just two reports telling one story — and the story is always about what the Fed does next.
What inflation actually is
Inflation is the rate at which prices rise over time. At 2 percent, things cost 2 percent more this year than last; at 6 percent, your money buys 6 percent less than it did a year ago. The Federal Reserve targets 2 percent as the healthy level — low enough that purchasing power holds, high enough that the economy doesn’t stagnate.
The catch is that measuring it isn’t simple. Different goods carry different prices, some change daily and some barely move, so you need standardized measures. The two that matter most to markets are CPI and PPI.
CPI: what you pay
CPI is the Consumer Price Index — the prices you, the consumer, actually pay. The Bureau of Labor Statistics tracks roughly 80,000 specific items every month, from groceries and gasoline to rent, clothing, healthcare, and restaurant meals, weighting each category by how much the average American spends on it. The result is a single number for how expensive life is getting.
It’s reported monthly, usually in the second week, in two flavors: month-over-month (the last 30 days) and year-over-year (the last twelve months). Markets watch both, but what really moves them is whether the number came in above or below what was expected.
PPI: what producers charge
PPI is the Producer Price Index — the prices manufacturers and wholesalers charge before goods ever reach you. Think of it as the price at the factory gate rather than the store shelf. The same BLS publishes it monthly, usually a day on either side of CPI.
Why care about a price you don’t pay directly? Because producer prices are a leading indicator. When wholesale costs rise, they eventually pass through to consumers — a hot PPI today often means a hot CPI next month. Wall Street watches PPI to predict where CPI is heading.
Headline vs core
Both reports come with a headline number and a core number. Headline includes everything; core strips out food and energy, which swing sharply on short-term supply shocks. Economists and the Fed lean on core to read the underlying trend, while the headline is what hits your wallet directly. Neither is “the real” number — they answer different questions.
Why markets react so violently
The Fed sets interest rates largely on the basis of inflation. Run hot, and the Fed keeps rates high to slow the economy and bring prices down — which pressures stock valuations and makes bonds more attractive. Cool off, and the Fed can cut, which generally lifts stocks. So when a print comes in hotter than expected, traders instantly reprice the odds of the next Fed move: stocks fall, bond yields rise, sometimes dramatically. A cool print runs the tape the other way.
Two reports, one story
So when a headline says CPI ran hot or wholesale inflation jumped, you know what’s happening underneath. The data is telling you where prices are headed; the market is telling you what it thinks the Fed will do about it. The distance between expectation and reality is exactly where the volatility lives — and it always resolves back to the same question of what the Fed does next.
Not investment advice. WTH Markets is editorial commentary, not financial guidance.
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