Resolves YES if in any monthly CPI release up to and including the release for Dec 2024 (to be published in Jan 2025) from the US Bureau of Labour Statistics, annual headline CPI inflation is negative.

That is, this market will resolve YES if any monthly value of CPI-U in the given timeframe is lower than it was in the same month of the previous year.

I will resolve based on the unrounded CPI-U figures, thus this market might resolve YES even if annual inflation is reported as 0.0% to one decimal place.