Yesterday, the front-month crude-oil contract experienced its largest single-day drop since January 1991. In today's session, news of an unexpected increase in U.S. crude supplies is pushing black gold even lower. The Energy Information Administration (EIA) reported that crude inventories rose by 3 million barrels during the past week to total 296.9 million. By contrast, analysts surveyed by Platts were expecting a decrease of 3 million barrels.

The EIA also noted that gasoline supplies climbed by 2.4 million barrels during the week ending July 11, while distillate stocks added 3.2 million barrels.

Following the surprise spike in crude inventories, August-dated crude shed more than $6 to trade at $132.50 per barrel.

Meanwhile, the Brazilian Oil Workers Federation, or FUP, is threatening a nationwide strike against state-run Petrobras (PBR). Platform workers in Brazil's Campos Basin kicked off a 5-day strike on Monday, but PBR reported yesterday that all platforms in the oil-rich region had resumed normal operations, thanks to its contingency teams.

In an effort to pressure the energy giant, FUP leaders have now given their approval to a 48-hour work slowdown across the country, which is set to begin on Thursday. No efforts will be made to cut production during the slowdown, but shift changes will be interrupted and facility access will be blocked as protests ensue.