NEW YORK (TheStreet) -- Petrobras stock is decreasing 5.2% to $5.83 in afternoon trading on Monday after U.S. and Brent crude prices plunged to a six-month low on lower demand in the U.S. and growing production in the Middle East. WTI crude is down 3.82% to $45.32 per barrel, while the Brent crude is falling 4.62% to $49.80 per barrel this afternoon, according to a CNBC.com index. The Organization of the Petroleum Exporting Countries is showing no indication it would lower production, despite the fall in prices and Iran's plans to increase production, Reuters reports. Iran will pump an additional 500,000 barrels a day once the sanctions are lifted and plans to increase production by a million barrels per day after a few months. Additionally, gasoline futures were down 5% as demand in the U.S.