Renewable Energy Group Inc. reported an operating loss of $2 million for the first quarter, compared with operating income of $77.1 million for the first quarter of 2013. The net loss attributable to common stockholders was $2 million, or 6 cents per share, compared with net income of $38.4 million, or $1.25 per share, for the year-ago quarter.  Compared with the first quarter of last year, REG sold 22 percent more gallons of biodiesel in the first quarter of 2014, while revenues decreased by 17 percent to $219 million. However, removing the impact of a retroactive $57.4 million tax credit benefit in the first quarter of 2013, first-quarter 2014 revenue would have been 5.8 percent higher than the year-ago quarter. "This quarter was very challenging, coming off an outstanding year," said Daniel Oh, REG's president and CEO. "While some of the challenges that affected the first quarter remain, in the near term we are focusing our efforts to respond when markets normalize, and on executing our longer-term strategies."