A Huge Bet on Supertankers Reverberates Through the Oil Market

A niche but crucial part of the oil market is being rocked by a huge bet from a South Korean tycoon who has amassed a large share of the tanker market — with help from one of the industry’s wealthiest men.

Over the past month or two, the Sinokor group has quickly moved to buy or charter a significant number of ships and now controls roughly 120 very-large crude carriers, according to estimates from several senior industry executives. Some market veterans said the huge position amassed by the company, overseen by shipowner Ga-Hyun Chung, is unprecedented in their experience.