Crude for December delivery posted its first loss in about 5 sessions today, as an analyst survey indicated expectations for a rise in U.S. petroleum supplies in tomorrow's weekly report from the Energy Department. What's more, an expected resumption of production at Petroleos Mexicanos also eased oil prices. By the close, the December contract had plunged $3.15, or 3.37%, to close at $90.38 per barrel.

Looking ahead to tomorrow's update on U.S. supplies, analysts surveyed by Platts expect U.S. crude inventories to show a buildup of 1.25 million barrels, while analysts at MF Global expect crude supplies to rise by 2.5 million to 3.5 million barrels on the week.

Turning to oil stocks, the CBOE Oil Index (OIX) was last off nearly 3% on the day, while the AMEX Oil & Gas Index (XOI) had dropped 2.85%. Dropping oil prices also had an impact on metals, as gold for December delivery dropped $4.80 an ounce to close at $787.80.