Petroleum-linked shares tumbled early Wednesday, on lower oil prices, pressuring US stocks, while some big technology shares were modestly positive.
ExxonMobil and Chevron (Euronext: CHTEX.NX - news) were among the biggest losers in the Dow as oil prices slid on worries about higher output from members of the Organization of the Petroleum Exporting Countries.
But large technology companies including Apple (NasdaqGS: AAPL - news) , Amazon and Microsoft (Euronext: MSF.NX - news) advanced modestly. Tech shares have been volatile for the last several weeks, with some analysts describing a rotation to disfavored sectors from after the Nasdaq (Frankfurt: 813516 - news) surged to a series of records this spring.
About 20 minutes into trading, the Dow Jones Industrial Average was down 0.2 percent at 21,441.82.
The broad-based S&P 500 lost 0.1 percent at 2,425.92, while the tech-rich Nasdaq Composite Index was flat at 6,111.05.
US markets were closed Tuesday for the Independence Day holiday.
Key events this week include the release of Federal Reserve meeting minutes, which are expected to shed light on the US central bank's thinking on raising interest rates further and Friday's release of the June employment report, expected to show an addition of 173,000 jobs.