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MACRO · PREDICTION CHECK · 11 SEPTEMBER 2026

The Inflation Direction Was Right, but Core Prices Were Stickier Than Expected

U.S. August PPI / CPI Prediction Check | 11 September 2026

Public ResearchActual vs Forecast
DIRECT ANSWER

ACIS broadly captured the direction of U.S. August inflation: PPI, monthly headline CPI and both annual CPI measures landed within the forecast ranges. The key miss was monthly core CPI at 0.3%, 0.1 percentage point above the base case. Inflation is not broadly out of control, but the policy balance is slightly more hawkish than the original base case.

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After the August inflation releases, the main ACIS directional call broadly held. Producer prices rose zero point four percent month over month, and consumer prices also rose zero point four percent, both within the forecast ranges. Headline CPI was three point four percent year over year and core CPI was two point four percent, also in line. The important miss was monthly core CPI at zero point three percent, one tenth of a percentage point above the base case. Inflation is not broadly out of control, but underlying price pressure remains sticky. High valuation and long duration assets therefore remain exposed to interest rate pressure, and the September policy path requires caution.

01 · PREDICTION CHECK

Actual results versus the 8 September forecast

IndicatorACIS forecastActualResult
PPI MoM+0.3% to +0.5%+0.4%Hit
Core PPI MoM+0.2% to +0.3%+0.3%Hit
PPI YoY+5.4%Hot upstream
CPI MoM+0.3% to +0.4%+0.4%Upper bound
Core CPI MoMAbout +0.2%+0.3%0.1 ppt hotter
CPI YoY+3.3% to +3.4%+3.4%Hit
Core CPI YoYAbout +2.4%+2.4%Hit

Core PPI uses final demand less foods, energy and trade services. Monthly changes are seasonally adjusted; annual changes are unadjusted.

02

The important miss was monthly core CPI

The base case assumed roughly 0.2%; the actual reading was 0.3%. A tenth of a percentage point does not signal a broad inflation breakout, but it shows that underlying consumer-price pressure is stickier than expected. The better description is hot upstream prices, energy-driven headline pressure and persistent core inflation.

03

The policy signal is slightly more hawkish

The preview argued that employment had given the Federal Reserve room to tighten, while CPI would decide whether it needed to. A 0.3% monthly core reading lands in the original slightly-hot scenario rather than the moderate one. It keeps a tighter policy path credible without proving that a rate move is certain.

04

Market read-through

  • Richly valued growth and software remain sensitive to high long-term yields.
  • AI hardware fundamentals may remain strong while valuation multiples face rate pressure.
  • Cash-generative financials and quality value may be relatively more resilient, but resilience does not remove valuation risk.
  • Ultra-long Treasuries are rate-sensitive assets, not cash substitutes.
  • A firm dollar and elevated real yields remain near-term constraints for digital assets.
05

How to judge the forecast

This should not be described as a perfect forecast. Most readings landed inside the ranges and the directional framework held, but monthly core CPI was hotter than the base case. The durable value is the preserved chain from ex-ante forecast to actual result to error analysis—not a victory lap.

06 · KEY QUESTIONS

What readers need to know

Did ACIS get the forecast right?Broadly yes on direction and ranges, but not perfectly: monthly core CPI was 0.1 percentage point above the base case.
Is inflation out of control again?The data do not support that conclusion. They show hot upstream prices, an energy lift to headline CPI and persistent core pressure.
Does this guarantee a September rate move?No. It strengthens the hawkish case, but the Federal Reserve will also weigh employment, financial conditions and the full data set.
Why preserve the original preview?Because a forecast can only be evaluated credibly when the ex-ante assumptions remain visible beside the outcome.

Sources and historical record

U.S. Bureau of Labor Statistics · August 2026 PPI U.S. Bureau of Labor Statistics · August 2026 CPI Original forecast | 8 September 2026
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