Crude oil dropped sharply Thursday, with futures ending under $70 a barrel, as petroleum stockpiles climbed and data showed dwindling demand in the U.S. November-dated futures dropped $4.69 to $69.85 in New York and have now slid more than 50% since the all-time high that was reached in July. Oil hasn't been below $70 in more than a year. Brent crude lost $4.48 to $66.32 a barrel. Gasoline futures declined by 16 cents to $1.62 a gallon, and heating oil fell 10 cents to $2.09 a gallon. Natural gas, however, was stronger. Stocks in the energy sector were generally to the upside. Exxon Mobil ( XOM), ConocoPhillips ( COP) and Chevron ( CVX) all rose. Tesoro ( TSO) and Valero ( VLO) also advanced. The U.S. Oil ( USO) ETF, which tracks crude prices, was down 2.3%.