The risk that oil prices could fall to $20 a barrel is rising, according to Goldman Sachs (GS). The Wall Street firm is out with a new forecast and says a persistant surplus of supply may require prices remain lower for longer than expected to rebalance the market. That rebalancing may happen at sharply lower prices, perhaps as low as $20 a barrel, according to the Goldman note. Also negative for oil today, Saudi Arabia says it won't back holding an emergency OPEC meeting aimed at stopping crude oil's slide. Zumiez (ZUMZ) shares are plunging after disappointing results and a weak forecast. Zumiez CEO says its mix of merchandise wasn't well received by shoppers. BMO has bought GE (GE) Capital Transportation Finance unit. The purchase price wasn't disclosed. Producer Prices are expected to fall in August due to lower energy prices. The University of Michigan releases its September Consumer Sentiment Index. It is the 14th anniversary of the terrorist attacks on the World Trade Center and the Pentagon.