Since that high last Wednesday, the S&P is down more than 7 percent. And on Tuesday, yields on 10-year United States Treasury bonds fell to their lowest levels on record, suggesting investors expect significant economic damage and accompanying Federal Reserve interest-rate cuts.

There remains huge uncertainty about how widely the virus will spread and how much damage it will do. But the financial world is realizing just how much is at stake — and how different this is from other recent hiccups in the global economy, notably last year’s trade war between the United States and China.

“It’s one thing if Wuhan is on lockdown, another if all of China is on lockdown, another if all of Asia is on lockdown, and another if the whole world is on lockdown,” said Patrick Chovanec, an adviser for Silvercrest Asset Management and an expert on the Chinese economy. “That’s why sentiment has shifted — because it’s very different to have one country on lockdown for a couple of weeks versus rolling lockdowns throughout the global economy.”

Since the end of the global financial crisis more than a decade ago, investors who have been the most alarmist about various risks have had a tendency to lose money. Global asset prices have been on a steady march upward despite the eurozone crisis, the end of the Federal Reserve’s quantitative easing, the trade war and every other problem that has occupied financial headlines.

So it is understandable if investors were quick to assume that coronavirus would follow a similar pattern — a temporary blip that reduced China’s growth for a quarter or two but had little lasting impact.