U.S stock index futures were slightly higher Tuesday, ahead of the German constitutional court ruling on whether Germany may contribute to the euro zone's rescue fund and as investors hoped the Federal Reserve will announce further stimulus measures later this week.
Earlier, Germany’s Constitutional Court confirmed that the ruling on the permanent European bailout fund, the European Stability Mechanism (ESM), will take place Wednesdaydespite a new court challenge. European shares traded slightly lower.
Expectations have been growing that the central bank will launch another round of quantitative easing on the heels of some recent weak economic data, most notably last week's monthly jobs report. (Read More: How to Trade the Fed's Next Likely Move)
Meanwhile, ratings agency Moody's wanred that the U.S. could lose its triple-A debt ratingif next year's budget negotiations do not produce a downward trend in the country's debt to GDP ratio.
On the economic front, U.S. trade deficit increased in July to $42 billion, as exports to Europe felland imports from China surged to a new record.
McDonald's reported a weaker-than-expected 3.7-percent gain in August same-store sales, hurt by Europe and the volatile global economy.