U.S. stock index futures edged higher on Monday, building a fourth days of gains, though developments in Japan, Libya and the Middle East kept alive the potential for volatile trading.

The Dow Jones industrial average <.DJI> gained 14.07 points, or 0.12 percent, to 12,234.66. The Standard & Poor's 500 Index <.SPX> rose 2.49 points, or 0.19 percent, to 1,316.29. The Nasdaq Composite Index <.IXIC> added 8.26 points, or 0.30 percent, to 2,751.32.

(Reporting by Chuck Mikolajczak)

Japan Libya