Stocks pushed higher Thursday, as investors reacted to economic reports that paint a mixed picture for the U.S. economy. The Dow Jones industrial average and the S&P 500 each climbed 0.6% after scoring their highest levels since December 2007. The Nasdaq also added 0.6%. Volume increased on both major exchanges, according to preliminary data. Homebuilders broke ground at an annualized rate of 954,000 units in December, the fastest pace in four