Stock exchange traded funds were lower Wednesday in volatile trading following the previous session’s across-the-board sell-off.

SPDR S&P 500 (NYSEArca: SPY) was down fractionally in morning action. The ETF dropped 2.6% on Tuesday and fell through its 200-day moving average. [Stock ETFs Tumble; S&P 500 Takes Out 200-Day]

The private sector added 114,000 jobs last month as the ADP report came in better than expected on Wednesday.

However, investors are looking forward to the July nonfarm payrolls report, which will cross on Friday in the week’s main event for economic data.

“It is hard to say how much of yesterday’s squeamish action in U.S. and European equities is due to worries over the Euro and/or the direction of the American economy,” Nicholas Colas, ConvergEx Group chief market strategist, wrote in a note Wednesday.

“The next important data point for the latter will be Friday’s Employment Situation Report, where consensus is 84,000 jobs added as a headline number and 100,000 added in the private sector. Our monthly review of the U.S. Treasury’s individual tax receipt data shows that these estimates may well be too optimistic. Last month saw a year-on-year decline of 0.3% in total personal tax receipts … the first such decline in 2011.”

Technical analysts are watching a developing so-called head-and-shoulders pattern in the S&P 500. [Pattern Developing?]

Gold ETFs opened higher Wednesday as the metal’s price climbed to another nominal record. [Gold ETFs Run]

SPDR S&P 500