On Monday evening, Apple warned its shareholders about the effects of the new coronavirus outbreak. Production of iPhones has been slowed because of quarantined workers, and the company expects to sell fewer products in China as the country grapples with the problem.

Revenue, Apple said, will take a hit, though it wasn’t ready to estimate just how big. It seemed the kind of warning, from a company worth $1.4 trillion and a mainstay of investors’ portfolios, that might inspire quite a sell-off on Wall Street. After all, if the supply chain wizards at Apple can’t keep things going because of coronavirus, what other problems might emerge that ripple through the global economy?

But Wall Street, in the end, mostly ignored it. The S&P 500 fell a mere 0.3 percent Tuesday, only to recover all of that ground and more Wednesday. By the close of trading Wednesday, even Apple stock recovered to nearly where it had been before the announcement.

It fits a pattern: The stock market has barely reacted despite the idling of countless factories in China as workers are quarantined, and despite fears that the virus could spread more widely and create further economic disruption across Asia and beyond. The S&P 500 is actually up 4.6 percent from its levels at the end of January, when the World Health Organization declared coronavirus a global health emergency.