Chevron lost $588 million in the fourth quarter of 2015, a setback that was unleashed by a slide in oil prices, leading Chevron to warn that a fresh round of expense reductions, including job cuts, would be in the offing for 2016, the company reported Friday. "Our 2015 earnings were down significantly from the previous year, reflecting a nearly 50 percent year-on-year decline in crude oil prices," said George Watson, Chevron's chief executive officer, in a prepared release.