Stocks ended mostly lower Monday, after the market reached two major milestones earlier today. The Standard & Poor's 500 index closed with a loss after crossing 1,800 for the first time Monday. The Dow Jones industrial average also reached 16,000 for the first time. Neither index closed above those levels, however. The S&P 500 fell six points, of 0.4 percent, to close at 1,791. The Dow edged up 14 points, or 0.1 percent, to 15,976. The Nasdaq composite gave up 37 points, or 0.9 percent, to 3,949.
