Inflation & CPI Explained

Inflation is the rate at which the general level of prices for goods and services rises over time, reducing purchasing power. It's the economic indicator that has dominated market narratives in recent years and is a critical factor in every trader's decision-making process.

How Inflation Is Measured

The two primary measures of inflation in the US are:

Consumer Price Index (CPI)

Published monthly by the Bureau of Labor Statistics (BLS), CPI measures the average change in prices paid by urban consumers for a basket of goods and services. This basket includes:

Housing (shelter) — ~33% of the index
Food — ~14%
Energy — ~7%
Transportation — ~6%
Medical care — ~7%
Other goods and services

Personal Consumption Expenditures (PCE)

Published by the Bureau of Economic Analysis (BEA), PCE is the Fed's preferred inflation gauge. It's broader than CPI and uses a different weighting methodology that accounts for substitution effects (when consumers switch to cheaper alternatives).

Headline vs. Core Inflation

Headline CPI/PCE: Includes all items, including volatile food and energy prices
Core CPI/PCE: Excludes food and energy

The Fed focuses more on core measures because food and energy prices fluctuate due to supply shocks (weather, geopolitics) rather than monetary conditions. If core inflation is sticky, the Fed is more likely to keep rates elevated.

Why Inflation Matters for Markets

Inflation directly influences central bank policy, which in turn drives asset prices:

High inflation → Tight monetary policy → Higher rates → Bearish for risk assets Low inflation → Accommodative policy → Lower rates → Bullish for risk assets

Impact on Asset Classes

Stocks:

Moderate inflation (2-3%) is generally benign for stocks
High inflation erodes profit margins and increases input costs
Extremely high inflation forces rate hikes that compress valuations

Bonds:

Rising inflation is terrible for bondholders — it erodes the real value of fixed coupon payments
TIPS (Treasury Inflation-Protected Securities) provide a hedge

Crypto:

Often marketed as an "inflation hedge" but has behaved more as a risk asset
Crypto rallied during high inflation in 2020-2021 (when rates were near zero) but sold off in 2022 (when rates rose to combat inflation)

Gold:

Traditional inflation hedge
Performs best when real yields (yields minus inflation) are negative

US Dollar:

The Fed raising rates to fight inflation typically strengthens the dollar

Reading a CPI Report

When a CPI report is released, focus on:

Headline number vs. expectation: Did it beat or miss?
Core number: Is underlying inflation accelerating or decelerating?
Month-over-month change: More granular than year-over-year
Shelter costs: The largest component — if it's coming down, headline will follow
Services inflation: More "sticky" and harder to bring down than goods inflation

Trading CPI Releases

CPI is released at 8:30 AM ET, usually on the second Tuesday or Wednesday of the month. It's one of the most volatile scheduled events:

Hotter than expected: Stocks sell off, dollar rallies, bonds drop, potential crypto weakness
Cooler than expected: Stocks rally, dollar weakens, bonds rise, crypto may benefit
In line with expectations: Usually a muted reaction, focus shifts to the details

Tips:

Reduce leverage into CPI releases
Don't jump in during the first 5 minutes — initial reactions often reverse
The month-over-month number matters more than year-over-year for forward-looking expectations

The Fed's 2% Target

The Federal Reserve targets 2% annual inflation (measured by PCE). When inflation runs significantly above 2%, the Fed tightens policy. When it falls below, they ease. This target serves as the anchor for all rate decision-making.

Key Takeaways

CPI and PCE are the primary measures of inflation in the US
Core inflation (excluding food and energy) is what the Fed watches most closely
High inflation leads to tight monetary policy, which is bearish for risk assets
CPI release days are among the most volatile trading sessions
Always know the consensus expectation before a CPI release