SK Innovation Co., which owns the country’s top refiner SK Energy Co., said Tuesday its net profit tumbled 36 percent last year from a year ago due to decreased margin in the refining business.

Net profit came to 757.03 billion won ($698 million) in 2013, compared with 1.18 trillion won a year earlier, the company said in a regulatory filing.

Sales fell 9.1 percent to 66.67 trillion won in the period, and operating profit dropped 18.7 percent to 1.38 trillion won.

The figures reflected earnings from SK Innovation and its subsidiaries such as SK Energy, SK Global Chemical Co. and SK Lubricants Co.

“Last year’s performance was sluggish as volatile oil prices and decreased demand for oil products caused the average refining margin to drop,” the company said.

In the October-December period, the company posted a net loss of 84.37 billion won, down from 262.20 billion won a year ago. The operating loss was 25.13 billion won compared with 210.39 billion won the previous year.

The company’s fourth-quarter sales fell 7.6 percent on-year to 15.86 trillion won.

The weak quarterly earnings stemmed from a stronger won that lowered the value of exporters’ dollar earnings, the company said.

The narrowing refining margin led SK Energy’s operating profit to tumble 79 percent to 57.8 billion won last year from a year ago, marking the second-lowest level since 2009, when it was 42.9 billion won. (Yonhap)