Crude oil fell, extending a fourth weekly decline on concern OPEC’s refusal to cut production will worsen a global glut. Saudi Oil Minister Ali Al-Naimi said OPEC’s biggest producer will seek to maintain market share and that global demand growth this year was slower than expected. Iraq plans to boost its production next year, Oil Minister Adel Abdul Mahdi said. Trading volatility stayed at the highest level in more than three years. “Saudi Arabia is not willing to give up market share,” said Kyle Cooper, director of commodities research at IAF Advisors in Houston. “With the U.S. production trajectory intact certainly in the next few months, it’s going to be a fight. It certainly looks like oil is heading toward $50.” Oil has slumped about 21 percent since OPEC decided against cutting its production target last month, prompting a plunge in the value of currencies from the Russian ruble […]