US August core PCE inflation slowed more than expected, but the decline came mainly from adjustments to statistical methodology rather than an actual easing of underlying price pressures.

Data released Wednesday by the US Commerce Department's Bureau of Economic Analysis (BEA) showed that the US August core PCE price index rose 3.0% year-over-year, below both market expectations and the previous reading of 3.3%. On a month-over-month basis, it rose 0.25%, also below expectations. The July core PCE monthly gain was revised down to 0.13%, matching June's pace, bringing the annualized growth rate of core PCE over the past three months down to 2%, returning to the Federal Reserve's 2% inflation target.

The headline PCE price index rose 0.3% month-over-month in August, in line with expectations, and rose 3.4% year-over-year, below the market consensus of 3.7%.

Following the data release, market inflation anxiety eased somewhat, US stock index futures briefly rallied, and traders reduced their bets on a Federal Reserve rate hike in October.

However, the decline in this data largely did not stem from a sudden cooling of prices themselves, but rather from the BEA's adjustment to the calculation methodology for the PCE price index.

From a longer-term perspective, inflation pressures have not fully subsided. The headline PCE price index rose 0.31% month-over-month in August, significantly higher than July's 0.05% and June's -0.10%. The annualized growth rate over the past six months rose to 3.6%, higher than the previous six months' 3.3% and the year-ago comparable period's 2.3%. The headline PCE rose 3.4% year-over-year.

Sharp Drop in Core PCE Year-over-Year: Methodology Adjustment Is Key

The BEA updated the calculation methodology for the PCE deflator this time and applied the new method retroactively to the first quarter of 2021.

Previously, RBC estimated that the methodology adjustment would lower the core PCE year-over-year growth rate by approximately 18 basis points and downgrade July core PCE from 3.3% to 3.1%. The actual results were broadly consistent with this estimate.

RBC analysis suggests the adjustment primarily involves three aspects:

First, the quantity indicator for portfolio management services was changed to a new calculation method based on US Bureau of Labor Statistics survey data, rather than the previous nominal price deflation method.

Second, computer software prices now use a new composite PPI and CPI deflator indicator.

Third, legal services use a new price deflator, as the previously used CPI indicator was deemed unable to accurately reflect relevant price changes.

Therefore, the drop in August core PCE year-over-year from 3.3% to 3.0% cannot simply be interpreted as a significant easing of US inflation pressures within a single month.

In other words, this "below-expectations" core PCE reading partly reflects statistical methodology and benchmark adjustments, rather than a simultaneous decline in actual price pressures in the economy.

Core PCE coming in below expectations suggests some easing of inflation pressures, while resilient consumer spending indicates the US economy still has support. The Federal Reserve is closely monitoring inflation and consumption data. The September employment report, along with inflation and consumption data in the coming weeks, will provide more basis for the October 28 interest rate decision.

Supercore Inflation Reaccelerates, Services Inflation Remains Stubborn

More notably, the services inflation measure excluding housing costs — "supercore" PCE — has not continued its previous cooling trend.

Data shows that supercore PCE year-over-year growth has rebounded, while the month-over-month gain expanded significantly.

This means that although headline core PCE fell notably due to statistical methodology adjustments, price pressures within the services sector remain.

The August core PCE increase still came mainly from services, with communication and education services prices rising particularly notably.

Therefore, if statistical methodology changes are distinguished from actual price changes, this report cannot simply lead to the conclusion that "US inflation has clearly cooled."

David Russell, Global Head of Market Strategy at TradeStation, said the data helps ease concerns arising from the recent sharp rise in US Treasury yields and strengthens the case for the Federal Reserve not to raise rates in October. However, he also noted that this is relatively lagging data and does not reflect the impact of recent diesel price increases.

US Consumers Are "Spending More, Earning Less"

Compared with the inflation data itself, the August personal income and consumption data are equally noteworthy.

US personal consumption expenditures rose 0.9% month-over-month in August, significantly higher than July's 0.1% gain and in line with market expectations. Adjusted for inflation, August personal consumption expenditures rose 0.6% month-over-month, the largest increase since March 2025. Spending on goods such as automobiles, furniture, and clothing all increased, as consumers maintained strong willingness to spend despite high oil prices and rising overall costs.

However, personal income rose only 0.2% month-over-month, below July's 0.3% and significantly below the market expectation of 0.5%.

Consumption growth significantly outpacing income growth means US consumers are increasingly relying on previously accumulated savings to sustain their spending.

Data shows the US personal savings rate fell further from a revised 4.6% in July to 4.1% in August, the lowest since November 2022.

At the same time, income growth has fallen to its lowest level since April 2022.

This means US consumption remains resilient for now, but the foundation supporting this consumption growth is changing: income growth is increasingly unable to keep up with spending growth, and households are beginning to draw down savings more heavily.

What the Market Really Needs to Focus On: The True Value Behind "3.0%"

From a market perspective, the drop in August core PCE year-over-year to 3.0% will undoubtedly temporarily ease pressure on the Federal Reserve to continue tightening policy.

But if this decline mainly stems from statistical methodology adjustments rather than broad-based actual price cooling, then the market needs to interpret this figure more cautiously.

Especially against the backdrop of reaccelerating supercore services inflation, consumption still growing at a relatively fast pace, and income growth continuing to slow, the US economy does not present a very clear combination of "rapid inflation decline and simultaneous demand cooling."

Therefore, the signals from this PCE report are actually quite complex:

On one hand, core PCE year-over-year unexpectedly falling to 3.0% provides new justification for the Federal Reserve to pause further rate hikes. On the other hand, methodology adjustments are an important reason for the significant decline in this data, services price pressures remain, and the continued decline in the household savings rate also indicates that consumption growth is increasingly relying on existing wealth.

For the Federal Reserve, the key going forward is not just the 3.0% figure itself, but whether inflation is truly continuing to converge toward the 2% target after stripping out statistical adjustment effects, and whether the gap between consumption and income can continue to be sustained.