(Crude oil, energy markets story updated for Wednesday close, Exxon Mobil oil spill response company)NEW YORK ( TheStreet) -- Oil futures delved into negative territory Wednesday after the government said crude oil inventories rose unexpectedly last week, and the markets took a turn for the worse in afternoon trading after cautious comments from Federal Reserve chairman Ben Bernanke in testimony on Capitol Hill. Crude stockpiles increased by 400,000 barrels for the week ending July 16, according to a weekly report issued by the Energy Information Administration. But the modest buildup defied analysts forecasts, provided by Platts, calling for a drawdown of 1.6 million barrels. It also countered estimates from the American Petroleum Institute released late Tuesday showing stockpiles declined by 241,000 barrels. That, in turn, sent the September delivery contract for crude on the Nymex down into negative territory. The contract settled on Wednesday afternoon at $76.56 a barrel, $1.02 below the previous settle price. The markets extended losses on Wednesday afternoon after Federal Reserve chief Ben Bernanke voiced more caution about the pace of economic recovery, and cited the ongoing issues of joblessness in the U.S. and European nations at risk of debt default. In the energy-specific context, reported fuel buildups in the EIA report also outpaced expectations. Gasoline inventories climbed up by 1.1 million barrels; analysts had thought those supplies would rise by 1 million barrels. Distillate fuels, too, added 3.9 million barrels, while forecasts had called for a more modest 1.6 million barrel buildup. September heating oil on the Nymex declined 5 cents to a settle price of $1.98 a gallon on Wednesday afternoon, while the September gasoline contract settled at $2.06 a gallon, a penny below the previous settle.