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) - Get Report

,

ConocoPhillips

(COP) - Get Report

and

Chevron

(CVX) - Get Report

all rose.

Tesoro

(TSO)

and

Valero

(VLO) - Get Report

also advanced.

The

U.S. Oil

(USO) - Get Report

ETF, which tracks crude prices, was down 2.3%.

This article was written by a staff member of TheStreet.com.