WASHINGTON — A gauge of U.S. manufacturing activity that fell to a 26-year low Monday followed similarly weak readings in Europe and China, fueling fears of a deepening global downturn.

The Institute for Supply Management's index of manufacturing activity for November fell to 36.2 from October's 38.9. The reading was worse than Wall Street economists' expectations of 38.4, according to a survey by Thomson Reuters. A figure below 50 indicates the sector is contracting.

The November reading is the lowest since May 1982, the Tempe, Ariz.-based ISM said.

The report came the same day that the National Bureau of Economic Research, a private group, said the U.S. economy has been in a recession since December 2007.

The stock market reacted badly to the gloomy economic reports and the official finding of a recession. The Dow Jones industrial average sank nearly 680 points, or 7.7 percent.

Economists said the manufacturing survey shows the U.S. economy is in a steep recession and that tough times will continue for manufacturers. It "points to one of the deepest contractions in industrial output in the post-World War II era," wrote Michael Feroli, U.S. economist at JPMorgan Chase.

Exports, a key source of strength for manufacturers over the past couple of years, are no longer a bright spot as major economies in Europe and Asia also slow.