New York - US stocks opened higher on Tuesday ahead of congressional testimony from Federal Reserve chair Janet Yellen expected to focus on monetary policy and Britain's referendum on remaining in the European Union.
Yellen last week outlined a cautious approach to hiking interest rates, in part due to uncertainty on whether Britons would vote Thursday to exit the EU.
Five minutes into trade, the Dow Jones Industrial Average was at 17 829.98, up 0.1%.
The broad-based S&P 500 added 0.1% at 2 086.26, while the tech-rich Nasdaq Composite Index rose 0.2% to 4 847.64.