At a time of year when crude stockpiles usually fall, a surprise build sends drillers tumbling

EnergyAssociated Press

Shares of the world's biggest oil companies a tumbling to multi-year lows on new data showing that U.S. crude inventories continue to rise at a time of year when they are typically in decline.

Commercial inventories increased by 2.6 million barrels last week, according an Energy Information Administration report Wednesday, jolting energy analysts who had been expecting levels to fall.

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The EIA says "U.S. crude oil inventories remain near levels not seen for this time of year in at least the last 80 years."

Crude prices fell at their lowest levels in more than six years. Prices are down 4.5 percent in afternoon trading.

Shares of Exxon Mobil Corp., BP Plc., Marathon Oil Corp., Chevron Corp., and ConocoPhillips all slid to multi-year lows.