Wall Street stocks were lower early Tuesday, opening a holiday-shortened week that includes a key employment market reading that could have a bearing on US monetary policy decisions.

Other major reports this week include Friday's August US jobs figures and manufacturing industry data later on Tuesday.

"We're seeing investors nervous and taking money off the table as we head into a particularly volatile period in the market," said Adam Sarhan of 50 Park Investments.

About 10 minutes into trading, the Dow Jones Industrial Average was down 0.5 percent at 41,370.40.

The broad-based S&P 500 dropped 0.8 percent to 5,603.46, while the tech-rich Nasdaq Composite Index fell 1.3 percent to 17,485.62.

Analysts attributed the weakness in the first trading session of September in part to seasonal dynamics, with Briefing.com noting it is historically the worst month for the markets.

Markets are looking ahead to the Federal Reserve's September 18 policy decision, widely expected to be an interest rate cut.