NEW YORK — Business at manufacturers from plastic companies to lumberyards plummeted to the lowest level in 26 years in October.

In what some economists called a sure sign of recession, the Institute for Supply Management said Monday its manufacturing index fell to 38.9, the lowest reading since September 1982. Any reading below 50 signals contraction.

"It's a report that confirms everything we learned in the last couple months — the economy is falling deeper into recession," said Stuart G. Hoffman, senior vice president and economist for The PNC Financial Services Group.

The index had been hovering near what economists call "the boom-bust" line for most of the year until its sharp fall in September brought it to the lowest level since the aftermath of the Sept. 11 attacks.

Monday's reading was dramatically below this past September's reading of 43.5 and far lower than economists' expectations of a reading of 41.5, according to the consensus estimate of Wall Street economists surveyed by Thomson/IFR.

The report is the latest in a string of grim indicators.

The nation's gross domestic product for the third quarter, which was released Thursday, showed the economy shrank at a 0.3 percent annual rate in the July-September quarter, as consumer spending saw the greatest decline in 28 years.

The Commerce Department's report on construction spending Monday showed a 0.3 percent decline in September, the third drop in the past four months.

While the construction decline was better than the 0.8 percent drop economists expected, total building activity is down 6.6 percent from a year ago.

Stocks inched higher in the first trading day of November. After their 14 percent decline in October, some investors feel stocks are cheap.

The Dow Jones industrial average was up 36.40, or 0.39 percent, to 9,361.41, by late morning. The broader Standard & Poor's 500 was up 1.97 to 970.72.