NEW YORK (AP) — Worldwide markets plummeted again Thursday, deepening a weeklong rout triggered by growing anxiety that the coronavirus will wreak havoc on the global economy.

The sweeping selloff gave U.S. stocks their worst one-day drop since 2011.

The Dow Jones Industrial Average tumbled nearly 1,200 points. The S&P 500 has now plunged 12% from the all-time high it set just a week ago. That puts the index in what market watchers call a “correction,” which some analysts have said was long overdue in this bull market, the longest in history.

The losses extended a slide that has wiped out the solid gains major indexes posted early this year.

Investors came into 2020 feeling confident that the Federal Reserve would keep interest rates at low levels and the U.S.-China trade war posed less of a threat to company profits after the two sides reached a preliminary agreement in January. Even in the early days of the outbreak, markets took things in stride.

But over the past two weeks, a growing list of companies issued warnings that profits could suffer as factory shutdowns across China disrupt supply chains and consumers there refrain from shopping.