South Korean prosecutors indict four major refiners over allegations of oil price collusion

South Korean prosecutors on Monday indicted four major domestic oil refiners for violating fair trade laws, alleging they colluded to drive up domestic fuel prices following the Middle East conflict.

HD Hyundai Oilbank, SK Energy, GS Caltex, and S-Oil were the four companies that breached the nation's fair trade act, according to Yonhap News Agency.

HD Hyundai Oilbank and SK Energy colluded on 14.2 trillion won ($9.2 billion) worth of oil sales, Yonhap reported, citing prosecutors. Factoring in GS Caltex and S-Oil, which allegedly mimicked those prices, the total anticompetitive impact stands at roughly 26 trillion won, the report said.

The investigation was initiated after domestic oil prices sharply rose following the U.S.–Iran conflict, prosecutors said, finding that collusion by pricing executives at two of the firms over the timing and scale of the hikes was the primary driver.

The prosecution said the collusion was not a standalone incident but a long-standing, systemic practice that surfaced during a time of global crisis.

In March, South Korean President Lee Jae Myung warned on X that oil refiners and corporations engaged in price-fixing would be held accountable, vowing to deploy all lawful measures against unethical business practices.

Shares of the oil refiners and their owners were still higher. S-Oil gained 6.08%, SK Innovation, a parent company for SK Energy, advanced 1.58% while HD Hyundai rose 1.21% and GS Holdings, which jointly controls refiner GS Caltex with Chevron through its energy unit, rose 6.99%.

S-Oil declined to comment. Hyundai Oilbank, SK Energy, GS Caltex could not be immediately reached for comment.