All eyes are on the U.S. stock market after Britain's historic vote to leave the European Union.
The British vote shook up financial markets around the globe on Monday, leading to sharp falls in stocks and the British pound.
The Federal Reserve says it is carefully monitoring developments in global financial markets.
In a statement it said, " The Federal Reserve is prepared to provide dollar liquidity through its existing swap lines with central banks, as necessary to address pressures in global funding markets, which could have adverse implications for the U.S. economy."
Dow was down more than 500 points after the U.S. Stock Market opening.
The S&P 500 and Nasdaq look set to plunge 3.5 percent.
In a statement from the White House, President Obama said: