Mexican state-owned oil company Pemex reported a nearly US$18 billion fourth-quarter loss on Monday after both crude output and processing slid, though the company said refining levels should rebound as major maintenance plans are completed. The company posted a 352.3bn (US$17.9bn) peso loss for the last quarter of 2017, blaming a weaker peso exchange rate and higher financing costs for its performance, according to a filing with the Mexican stock exchange.