Major index futures are all down 0.2 percent: Dow Jones at 13,177. S&P 500 at 1,409, and Nasdaq 100 at 2,767.
Traders are waiting for data on July sales of previously occupied homes, and release of the July Federal Reserve meeting minutes.
European markets are lower as European leaders meet with Greece, which has asked for more time to meet its debt reduction targets. Britain's FTSE 100 index is down 1.1 percent. Germany's DAX dropped 0.8 percent. France's CAC 40 slipped 0.7 percent.
Asian markets all closed down after Japan posted a trade deficit for July.
Stocks to watch include Dell, which posted weak PC sales and a disappointing forecast, and Williams-Sonoma Inc., which reported a 10 percent profit jump.