U.S. stock futures are falling as spreading recession fears power a global sell-off in all investments seen as risky.

Markets in Asia closed sharply lower. The broad STOXX 50 index of European shares was down 1.6 percent. U.S. markets have fallen for four straight sessions, driving the S&P 500 index down more than 7 percent this week.

Treasury yields remain near record lows as traders amass lower-risk bets.

Leaders of the world's leading economies pledged late Thursday to take the steps necessary to restore market stability. But overseas markets fell anyway.

At 7:45 a.m. Eastern time, S&P 500 futures were down 15, or 1.3 percent, at 1,108. Dow futures were down 125, or 1.2 percent, at 10,525. Nasdaq 100 futures were off 29, or 1.4 percent, at 2,145.