WASHINGTON, Sept. 23 -- Twenty-nine minutes and forty seconds after Kevin Warsh left the Federal Reserve's press conference room on Wednesday, the Dow Jones Industrial Average had surrendered every point it added on the rate decision itself. The Nasdaq Composite had not. By Thursday's close, the gap between those two facts had become the defining story of the week: the stock market was operating as two separate economies.

The Federal Reserve raised its benchmark rate by 25 basis points on September 16, bringing the federal-funds target range to 3.75%-4%. It was the first rate increase since 2023.

Chair Warsh's decision not to take questions intensified the market reaction. The news conference lasted 29 minutes and 40 seconds-the shortes...