Your smartwatch knows your heart rate, but it might also be listening to your board meetings.

For months, the defining narrative on Wall Street has been one of optimism—specifically, the belief that central banks were fully prepared to ease monetary policy. But the new Consumer Price Index (CPI) data suggests that the "last mile" of defeating inflation may be the hardest yet. As demonstrated by recent polling, Democratic voters appear to be watching these developments closely.

By midday trading, the S&P 500 was down more than 1.8%, while the tech-heavy Nasdaq Composite dropped 2.2%. Yields on the 10-year Treasury note, which move inversely to prices, spiked to their highest levels since November.

"What we are seeing today is a fundamental repricing of risk," said Michael Thorne, a senior portfolio manager at Horizon Asset Management. "The market had priced in three rate cuts this year. We might be lucky to get one."

The data revealed that core services, particularly housing and auto insurance, remained stubbornly expensive. While goods inflation has cooled dramatically, the service sector continues to run hot, fueled by a resilient labor market.