Exxon Mobil badly missed earnings forecasts on Tuesday as it took a $2 billion impairment charge, mostly due to the company lowering the value of some of its U.S. gas assets. Excluding the impairment, earnings were higher than the year-ago period.

Persistently low oil prices and weaker profit margins in Exxon’s refining business also weighed on earnings for the full year, according to CNBC. “Financial results for the year were negatively impacted by the prolonged downturn in commodity prices and the impairment charge,” Chairman and CEO Darren Woods said in a statement.

Shares of Exxon rebounded to trade slightly positive after edging lower ahead of market open Tuesday.

Exxon reported fourth-quarter earnings of $1.7 billion, or 41 cents a share. In the period a year ago, the oil giant reported earnings of $2.8 billion, or 67 cents a share. Revenues for the quarter were $61.01 billion. Analysts expected Exxon to report earnings of 70 cents per share on sales of $62.28 billion.

Fourth-quarter earnings fell from a year ago in all three of the company’s major segments: exploration and production, refining and chemicals. The impairment resulted from the company’s review of its reserves. Last week, the company announced a dividend of 75 cents, unchanged from the third quarter.