NEW YORK, May 4 (Xinhua) -- U.S. stocks ended higher Thursday with the Dow refurbishing a six-year high on robust sales gains for April, as oil prices plunged below 70 dollars.

    World crude oil prices plunged on Thursday for the second straight day, on an optimistic U.S. weekly energy stocks report showing improved supplies.

    New York's main contract, light sweet crude for delivery in June, fell 2.34 dollars to end at 69.94 dollars a barrel, after hitting 69.30 dollars.

    The Labor Department said Thursday that U.S. productivity grew at an annual rate of 3.2 percent in the January-to-March quarter this year, rebounding from a fall of 0.3 percent in the previous quarter.

    The pickup in productivity, the amount an employee produces for every hour on the job, was stronger than the 2.8 percent growth rate that analysts had been expecting.

    Wal-Mart, the world's largest retailer, said sales this month at stores open at least a year may climb 2 percent to 4 percent. In April, they rose 6.8 percent, the biggest gain in almost three years.

    Target Corp., the No. 2 U.S. discount retailer, said April sales at stores open at least a year rose 10.4 percent, more than its forecast.

    At the closing time, the Dow Jones Industrial Average rose 38.58, or 0.34 percent, to end at 11,438. 86, its highest close since Jan. 19, 2000. The Standard & Poor's 500 Index was up 4.40, or 0.34 percent, to 1,312.25, and the Nasdaq composite index surged 19.93, or 0.87 percent, to 2,323.90. Enditem