Fed’s Stern Message Amplifies Worries About Stock Valuations

The prospect of faster-than-expected monetary tightening has rattled Wall Street, dragging the S&P 500 deeper into bear territory Tuesday and forcing investors to reassess a stock market that doesn’t look cheap even after its dramatic selloff.

It has been an ugly spell in markets, reflecting concerns about how the economy will hold up as the Federal Reserve embarks on its sharpest campaign of interest-rate increases in decades. Investors expect an increase of 0.75 percentage point on Wednesday, which would be the largest since 1994. 

Stocks were narrowly mixed Tuesday, with the Dow...