At 1400 GMT the blue-chip Dow Jones Industrial Average opened off 89.46 points (0.70 percent) at 12,718.05, after trading flat on Tuesday.
The broader S&P 500 index fell 9.13 points (0.67 percent) to 1,347.49, while the tech-rich Nasdaq Composite lost 7.56 points (0.27 percent) to 2,834.06.
Payrolls firm ADP said private companies added 179,000 jobs, slowing from 207,000 net new jobs in March. Analysts had projected that nonfarm payrolls would grow by 200,000 in April.
‘Early losses came from declines in the international markets on weakness in commodities and as traders focused on the headwinds facing the global economy,’ said Charles Schwab analysts.
Shares of China's top Internet social network RenRen, trading for the first time on the New York Stock Exchange, rose to $18.20 from their IPO price of $14 per American depositary share (ADS).
Tech stocks were helped by chip equipment maker Applied Materials's $4.9 billion acquisition of Varian Semiconductor, in an offer that put a 55 percent premium on Varian's share price. Applied shares were up 0.89 percent while Varian's soared 51.1 percent.
The bond market rose. The yield on the 10-year Treasury fell to 3.25 percent from 3.27 percent late Tuesday, while that on the 30-year bond slipped to 4.36 percent from 4.37 percent.
Bond yields and prices move in opposite directions.