Dow Jones industrial futures moved up 85 points to 12,765. S&P futures added 11 points to 1,368. Nasdaq 100 futures climbed 19 points to 2,716.
After several weeks of respite from Europe's debt crisis, the yields on Spanish and Italian bonds have started climbing again recently. That indicates investors aren't convinced they can reduce their debt loads and are more leery of lending to them.
Compounding concerns about a faltering recovery in the U.S. are indications that China's growth is slowing. The country reports its first-quarter gross domestic product on Friday.