NEW YORK (AFP) – Jobs and manufacturing data showing deep weaknesses in the US economy sent the US stock market plunging Thursday, wiping out the gains of previous days.

The Dow Jones Industrial Average dropped 279.14 points (2.22 percent) to 12,290.65, with all 30 of the blue chips in the losing column, led by Alcoa and Caterpillar, both down 4.3 percent.

The broader S&P 500 index fell 30.65 points (2.28 percent) to 1,314.55, while the tech-heavy Nasdaq Composite shed 66.11 points (2.33 percent) to 2,769.16.

The first data release of the month upheld the glum picture of the past two weeks. Payrolls firm ADP said the private sector added 38,000 jobs in May, well below the 170,000 expected.

Meanwhile the Institute of Supply Management's manufacturing survey plummeted nearly seven percentage points from April to a 19 month low, as new orders alone dropped by almost a fifth.

"The sharp decline... will only add to fears that the economy has hit another soft patch," said Capital Economics analyst Paul Ashworth.

The market was not helped when, late in the session, Moody's again downgraded Greek debt and gave it a negative outlook, raising the already high stakes in rescue negotiations for the imperiled eurozone member.

Also driving the sellers was news that China's manufacturing sector expanded at the slowest pace in 10 months in May, as measure by the HSBC China Manufacturing PMI, or purchasing managers index.

Big industrial groups that gain a lot from Chinese growth were hit: in addition to Caterpillar, Deere and Co. lost 3.9 percent, Cummins 4.4 percent, and Boeing 3.4 percent.

Tech stocks were dragged down by chip-makers: Micron fell 6.3 percent, Intel 2.3 percent, Applied Materials 5.1 percent, Nvidia 4.5 percent, and Texas Instruments 3.8 percent.

Also hitting tech was Microsoft's 2.3 percent drop and a 4.7 percent plunge in Nokia's US-traded shares. Rumors spread during the day said Microsoft would take over the struggling cellphone maker. Microsoft said it does not comment on rumors.

Bond prices rose. The yield on the 10-year Treasury bond fell to 2.97 percent from 3.05 percent late Tuesday, while that on the 30-year bond dropped to 4.15 percent from 4.22 percent. Bond prices and yields move in opposite directions.