The Federal Reserve's preferred inflation tracker shows cooling prices. Here's the impact on rates.

An inflation measure closely tracked by the Federal Reserve slowed to its smallest annual increase in three years, prompting some Wall Street economists to forecast an increased likelihood that the central bank could cut rates in September. 

The personal consumption expenditures index, or PCE, rose 2.6% in May on a year-over-year basis, the U.S. Commerce Department said on Friday. That represents its lowest increase since March 2021, according to EY senior economist Lydia Boussour in a Friday report, adding that it signals "cooler consumer spending momentum and easing inflation."

The Federal Reserve earlier this month scaled back its forecast to just one rate cut in 2024 from its prior expectation for three reductions due to stubborn inflation, which remains higher than the central bank's 2% annual target. Friday's PCE numbers could portend an increasing likelihood that the Fed could cut rates at its September meeting, Wall Street economists said.