U.S. stock index futures pointed to a lower open on Tuesday, as investors kept an eye on the price fluctuations in oil, amid speculation over when the Federal Reserve could raise interest rates.
The Dow Jones index was down some 150 points, while the S&P 500 was down 18 points and the Nasdaq down 33 points.
Markets had been choppy on Monday as concerns of a possible interest rate hike in September by the U.S. central bank added volatility to markets both in the U.S. and overseas.
However, U.S. stocks ended the session sharply up on Monday, after Fed Governor Lael Brainard said it would be wise for the central bank to keep monetary policy loose. Meanwhile Atlanta Fed President, Dennis Lockhart said a "serious discussion" on raising rates was warranted at the central bank's next meeting.
The positive sentiment from the U.S. on Monday failed to completely lift international markets on Tuesday however, with Asia-Pacific indexes closing mostly mixed, and Europe trading in a mixed range during its morning trade.
Aside from the Fed, oil has added pressure to the markets on Tuesday as increased oil drilling activity in the U.S. remains a key concern. Meanwhile the International Energy Agency warned in its latest report that markets would have to wait "a while longer" for the oil market to rebalance.
Crude futures posted solid losses on Tuesday, with U.S. West Texas Intermediate last standing around $45.28 per barrel, while Brent hovered at $47.43.