Ever since the jobs report on November 3rd, today's CPI report was in focus as the next major fundamental focal point for the bond market. As 10yr yields bounced in a range of 4.5 to 4.65, any major deviation from expectations in CPI was likely to elicit a break of that range. Breaking the ceiling would have been unfortunate, but boring (considering the recent 5%+ levels would likely require more data). Breaking the 4.5% floor is far more interesting, and thanks to CPI coming in a mere 0.1% lower than expected, that's what we have.
As for the extreme relevance and importance of today's data, let it never be doubted. A mere 0.1% deviation from the forecast is all it took for bonds to have an even bigger move (both in terms of volume and outright yield) than seen after this month's jobs report. The only caveat would be that NFP hit at the end of what was already a very big move for the week--a fact that likely sapped some of the volume and buying that might have otherwise been seen.