Price Measure Says Rate Can't Fall as Traders Expect

The key to whether the Federal Reserve continues to cut interest rates after this week may hang on the wall behind economist Brian Sack's desk in Washington.

Sack, head of monetary and financial market analysis at the Fed in 2003 and 2004, uses a chart that plots forward rates measuring investor expectations for inflation in five years. The gauge is so accurate that Sack and his colleagues persuaded the central bank to use it to help set policy. The chart is autographed by former Fed Chairman Alan Greenspan.