What is the Consumer Price Index?

The Consumer Price Index for All Urban Consumers (CPI-U) is the most widely followed measure of inflation in the United States. Published monthly by the BLS, it tracks changes in the prices paid by urban consumers for a market basket of goods and services covering approximately 93% of the US population. The basket includes categories such as housing, food, transport, energy, medical care, apparel, and recreation, with housing carrying the largest weighting at around 32%.

The BLS collects price data from tens of thousands of retail and service establishments across the country. The resulting index is expressed as the percentage change against the same month one year earlier (the year-over-year or YoY rate) and as the month-over-month (MoM) change. Core CPI, which strips out volatile food and energy components, is watched closely by the Federal Reserve (the Fed) as a measure of underlying inflation trends.

CPI is released roughly 12 to 13 days after the reference month ends. The September 2026 release covers price changes in August 2026, giving markets a timely read on whether inflationary pressures are easing or persisting.

US CPI Release: September 11, 2026

This release takes on particular importance given its proximity to the FOMC meeting on September 16, 2026. It will be the final CPI print before the Fed delivers its rate decision, making it one of the most market-sensitive data points on the calendar for the autumn of 2026. The most recent confirmed reading was 3.8% year-over-year for April 2026, the highest annual inflation rate since May 2023, driven by energy prices rising 17.9% on an annual basis.

Month-over-month, consumer prices rose 0.6% in April and 0.9% in March, reflecting the broad impact of higher oil prices. Core CPI rose to 2.8% year-over-year in April. Consensus forecasts for the August reading will be available closer to the release date; at time of publication, the trajectory points to inflation remaining elevated above the Fed’s 2% target.

Why This CPI Release Matters

The September 11 release lands just five days before the FOMC decision on September 16, giving Fed policymakers minimal time to fully digest the data before their meeting. However, the print will shape market pricing of rate expectations and is likely to trigger significant moves in Treasury yields, the US dollar, and equities immediately upon release.

Consumer price inflation has risen sharply through 2026, with the annual rate reaching 3.3% in March and 3.8% in April, driven by an oil price shock linked to geopolitical tensions in the Middle East. Gasoline prices rose 28.4% year-over-year in April, pushing total energy costs up 17.9%. The question for August data is whether energy prices have stabilised or whether second-round inflationary effects (such as rising transport and services costs) are entrenching.

For bonds, a high reading would push yields upward as markets price out any prospect of near-term rate cuts. For equities, persistent inflation pressure is most negative for growth and rate-sensitive sectors. The US dollar would likely strengthen on a hot print, while a cool reading would trigger the opposite moves across all asset classes.

What to Watch For

The market’s response will depend on where the headline print lands relative to prevailing expectations:

• Above consensus: A reading at or above 3.8% would signal that inflation is not cooling ahead of the Fed meeting, reinforcing expectations of a hold in September and potentially pricing in further hikes. Treasury yields and the US dollar would rise sharply; equities would sell off, led by growth sectors.
• In line with consensus: A reading in line with expectations would reduce volatility, with markets focused on the Fed’s forward guidance the following week rather than reacting to the inflation data alone. Attention would shift to sub-components, especially shelter and core services.
• Below consensus: A softer print, say below 3.0%, would be interpreted as progress towards the Fed’s 2% target and would increase expectations of a September rate cut. Bonds would rally, equities would rise broadly, and the US dollar would weaken. This outcome would represent a significant shift in the inflation narrative.

Energy price volatility remains the key swing factor. Should crude oil prices moderate through the summer, the August reading could show meaningful relief on the headline figure even if core inflation remains sticky.

Historical Context

Source: US Bureau of Labor Statistics. October and November 2025 data were not published due to the US government shutdown. MoM and core figures not available for all periods shown.

Market Positioning

As the September 2026 FOMC meeting approaches, Fed funds futures and bond markets will increasingly reflect the cumulative picture painted by the July and August CPI reports. Should both releases show continued elevation, the probability of a rate cut at the September meeting would be near zero. A meaningful softening in both prints would increase the chances of a 25 basis point reduction, which would represent a shift in the monetary policy cycle.

Equity markets have been navigating a challenging environment as higher borrowing costs weigh on valuations and corporate margins. The August CPI reading will be pivotal in determining whether the second half of 2026 brings relief or further pressure on rate-sensitive sectors. Fixed income investors will be watching shelter and services components most closely as leading indicators of where the broader inflation trend is heading.

Related Events

• US CPI Report August 2026 – The preceding monthly release covering July 2026 data, providing crucial context for the September reading.
• FOMC Rate Decision September 2026 – The Federal Reserve’s rate decision on September 16, just five days after this CPI release.
• ECB Rate Decision September 2026 – The European Central Bank’s policy meeting on September 10, providing a global monetary policy comparison.

Frequently Asked Questions

What does the CPI measure?

The CPI measures the average change in prices paid by urban consumers for a fixed basket of goods and services, including housing, food, transport, energy, and medical care. It is the most widely followed measure of consumer price inflation in the United States, published monthly by the Bureau of Labor Statistics.

When is the September 2026 CPI report released?

The September 2026 CPI report will be released on Friday, September 11, 2026, at 8:30 a.m. Eastern Time. The report covers price changes during August 2026.

Why is the September 2026 CPI particularly important for markets?

The September 11 CPI release falls just five days before the FOMC rate decision on September 16, 2026. It will be the final major inflation reading before the Fed announces its policy decision, making it one of the highest-impact data points of the quarter. A significant surprise in either direction is likely to cause sharp moves in equities, bonds, and the US dollar.