Futures wavered ahead of the open Tuesday as traders took a cautious stance after the long weekend, waiting to see if economic growth will return to the U.S. and whether concerns over Greek debt can be eased.
Investors are expected to react to S&P's statement that any rollover of Greek debt would be considered a default.
That statement once again unsettled investors, but since then, the Financial Times has reported that the European Central Bank will continue to accept Greek government bonds as collateral until all three rating agencies declare that Greece is in default.
Stocks closed sharply higher Friday to finish their best week almost two years.
The Commerce Department releases May factory orders data at 10 am ET. Economists in a Reuters survey expect a rise of 1.0 percent compared with a 1.2 percent drop in the prior month.
Later this week, the focus will shift to jobs, with key employment data out on Wednesday, Thursday and Friday.
Baidu and Microsoft gained following news the Chinese search-engine giant will team up with the Dow component for English-language search.