Marathon Petroleum (NYSE:MPC) reported fourth-quarter earnings yesterday and handily beat analyst estimates, while refining margins continued to increase due to discounted crude feed stocks. For the quarter, income from operations topped $1.4 billion, and while increased pipeline activity can pinch the already outsized margins, the future still looks bright. Marathon completed its Detroit heavy refinery expansion, increasing the capacity by 80,000 barrels of oil per day, which will expand its growing profits from exporting its refined products. Check out the video below for more information on Marathon's completed quarter. 

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