When the official consumer price index (CPI) came out last week, it was an unpleasant surprise to many economists. One, in fact, that signaled the Fed would likely raise its benchmark interest rate by at least a 75-basis point—if not more.

"It's becoming more apparent to market participants that the amount of tightening from the Fed thus far has not been enough to cool the economy and bring down inflation," said Charlie Ripley, senior investment strategist for Allianz Investment Management, in an emailed note.

Marcus & Millchap concurs. "In August, the headline Consumer Price Index recorded a year-over-year increase of 8.3 percent, slightly below the 8.5 percent rise recorded the month prior," the firm writes, as fuel prices have seen a sharp decline. "The core CPI measure, excluding food and energy, advanced at a faster pace, however, ascending 6.3 percent year-over-year in August compared to 5.9 percent in July."