Stocks are ending slightly lower after another bumpy day. Major indexes wavered between gains and losses for most of the day Tuesday, then ended barely in the red. Energy companies once again suffered the biggest losses as the price of oil took another tumble. Consol Energy sank 12%. The Dow Jones industrial average gave up 12 points, or 0.1%, to 16,014. The Standard & Poor's 500 index slipped 1 point to 1,852. The Nasdaq composite edged down 15 points, or 0.4%, to 4,268. (More Dow Jones stories.)