S-Oil Corp., a major oil refiner in South Korea, said Wednesday its third-quarter net profit plunged 41.3 percent from a year earlier due to decreased cracking margins.

S-Oil posted a net profit of 30.2 billion won ($26.7 million) in the July-September period, compared with a net profit of 51.5 billion won a year earlier, the company said in a regulatory filing.

The company said decreased cracking margins caused by weak demand amid the coronavirus pandemic are to blame for the sharp decline in net profit.

The benchmark Singapore complex margin -- a key measure of oil refining companies' profitability -- fell to minus $2 per barrel in the third quarter, compared with $3.9 from a year earlier.

Singapore is the regional trading hub of the benchmark Dubai crude.

The margin is the difference between the total value of petroleum products coming out of an oil refinery and the cost of crude and related services, including transportation.

South Korean refiners usually say their break-even point is between $3.5 and $4.5 per barrel.

S-Oil shifted to an operating loss of 9.2 billion won from an operating profit of 230.7 billion won a year earlier.

Sales fell 37.5 percent on-year to 3.89 trillion won from 6.23 trillion won.

Saudi Aramco, the world's largest oil company, is currently the largest shareholder of S-Oil, with a 63.41 percent stake. (Yonhap)