Key takeaways: Traders on the Kalshi prediction market believe the odds that inflation will set a new year-to-date high in 2026 are less than one in three.
Traders expect headline CPI to rise 3.6% year over year, compared with 3.4% in August.
On September 10, 2026, in Chicago, Illinois, consumers shopped at a grocery store.
Traders on the prediction market platform Kalshi believe inflation has most likely already reached its peak for the year, but it will not fall back quickly in the near term.
The U.S. Bureau of Labor Statistics will release the September Consumer Price Index (CPI) on Wednesday at 8:30 a.m. Eastern Time.
Traders expect September CPI to rise 3.6% year over year, in line with the consensus forecast of economists surveyed by FactSet.
That would be higher than the 3.4% year-over-year increase in August.
However, speculative trading on the Kalshi platform shows the probability that inflation will set a new high in 2026 is slightly less than one-third.
Earlier year-over-year inflation readings had shown periodic spikes.
The platform's inflation-related event contracts allow traders to bet on whether September CPI will breach various thresholds, or whether inflation will reach specific levels within 2026.
Contracts are ultimately settled based on official data released by the U.S. Bureau of Labor Statistics.
FactSet data show the market expects core inflation to remain unchanged at 2.4% year over year, in line with economists' forecasts.
Core inflation excludes fluctuations in food and energy prices.
But traders judge that core inflation will remain elevated for the rest of 2026.
The probabilities shown by the trading market indicate that the chance of core inflation falling below 2.2% this year is only 6%.
The last time annual core inflation was below that level was in 2021, before the current inflation surge began.
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