Wall Street Rewrites Market Playbooks for Pandemic’s Second Wave

As the world braces for a second wave of infections from the coronavirus, stocks are priced for a booming global economy, bonds point to a protracted downturn and currency volatility is rising.

Investors are increasingly uneasy with these conflicting signals among asset classes, but they are also resigned to them, and have adjusted their playbooks accordingly.

Tried-and-tested strategies that directed buyers into stocks in good times and bonds in bad times began to unravel in the face of unconventional monetary policy a decade ago. They are being dropped now as...