CPI Release
Overview
The CPI (Consumer Price Index) release is a statistical procedure that measures and regularly publishes changes in the price level of a representative basket of goods and services that households in a country purchase in everyday life. As the most representative indicator of inflation, it is treated as core data that shapes central banks' interest rate decisions, governments' fiscal policy, and financial market fund flows. Because a single released figure can overturn expectations for the policy rate path, market participants adjust positions around the release time.
Main Content
Definition and Significance of CPI
The Consumer Price Index is a statistic that indexes price changes of goods and services purchased by urban households for daily consumption, with a certain point in time set at 100. It is calculated as a weighted average using hundreds of items representing household expenditure categories such as food, housing, transportation, healthcare, education, and communications as samples. CPI is also used as a standard for converting nominal wages into real wages or adjusting institutional wages such as pensions and minimum wages, so it has ripple effects across society and the economy beyond being a simple market indicator.
Releasing Agencies and Schedule
In the United States, the Bureau of Labor Statistics (BLS) releases the previous month's CPI around the middle of each month, and also publishes Core CPI excluding food and energy. In South Korea, Statistics Korea releases the previous month's consumer price trends at the beginning of each month, and the Bank of Korea updates its inflation forecast based on this. In the eurozone, Eurostat; in China, the National Bureau of Statistics (NBS); and in Japan, the Ministry of Internal Affairs and Communications each serve as the releasing agency. Release times are announced in advance, designed so that market participants receive information at the same moment.
Calculation Method
CPI is based on the Laspeyres formula. It fixes the composition of the consumption basket at a base period, then multiplies each item's price change rate by its share of consumer expenditure as a weight and sums them. Item weights are updated annually or biennially, and recently there have been increasing attempts to improve timeliness by using online purchase data and credit card transaction data. However, substitution bias and quality adjustment issues have long remained subjects of debate.
Impact on Markets
CPI releases trigger immediate volatility across stock, bond, foreign exchange, and commodity markets. An inflation rate above expectations raises tightening concerns, pushing bond yields up and weighing on stock prices, while a figure below expectations stimulates easing expectations and increases preference for risk assets. In particular, because expectations for the Federal Reserve's policy rate path can be greatly shaken by a single CPI release, many assessments say that the price volatility in the minutes immediately after release is larger than for any other indicator.
Consumer Prices in South Korea
In South Korea, Statistics Korea publishes year-on-year and month-on-month inflation rates through the 'Consumer Price Trends' at the beginning of each month. It also provides core inflation excluding highly volatile items such as agricultural products and petroleum, and OECD-style core inflation excluding food and energy. The Bank of Korea has set an inflation target of 2%, and CPI is a key basis for judgment at monetary policy direction decision meetings.
Latest Trends
The environment surrounding CPI releases in 2024–2025 can be summarized in three main points. First, as inflation that surged after the pandemic converges to the low-to-mid 2% range in major countries, disinflation is progressing. Second, as the U.S. Federal Reserve entered a rate-cut cycle from the second half of 2024, the market sensitivity of CPI releases has increased further. If core CPI comes in stickier than expected, the interpretation that the timing of cuts will be delayed is immediately reflected. Third, the rigidity of housing costs and service prices, and energy price fluctuations due to geopolitical risks, have emerged as key variables determining the direction of CPI. South Korea also showed inflation around 2%, but agricultural product prices and increases in public utility rates are acting as variables. In addition, the digital transformation of statistical calculation methods, such as AI-based real-time price index calculation and expanded use of alternative data, is progressing rapidly.
Related Topics
- [[Consumer Price Index]]
- [[Inflation]]
- [[Policy Rate]]
- [[Federal Reserve]]
- [[Monetary Policy]]
- [[Producer Price Index]]
- [[Real Wage]]