Why stock-market investors keep falling for Fed ‘pivot’ talk — and what it will take to put in a bottom

Should you buy stocks now, or wait?

Timing the market has been a nagging question for investors ever since stocks began their decline by roughly 25% in January of this year. The right answer likely hinges on whether or not the Federal Reserve follows through with plans to raise its benchmark interest rate to 4.5% or higher, as market-based indicators and the Fed’s latest batch of projections anticipate.

Global markets are on edge about the possibility of an emerging-markets crisis resulting from higher interest rates and a U.S. dollar at...