International oil prices returning above $100 per barrel have created a sharp split in South Korean equities, lifting oil refiners and petrochemical companies while pressuring airlines that bear higher jet-fuel costs. Heunggu Oil rose 20.02% to ₩14,510 on the 10th, while Korea Petroleum and Joongang Energy also gained. Lotte Chemical and Korea Petrochemical Ind. posted double-digit advances the previous day. WTI settled at $96.05 per barrel on the 9th, up 3.25%, while Brent crude moved above $100 amid U.S.-Iran clashes, vessel attacks near the Strait of Hormuz and Houthi strikes on Saudi Arabia. Tight energy supplies have also pushed European gas, Northeast Asian LNG and U.S. diesel prices higher. Analysts say the durability of refining margins, rather than the oil-price peak alone, will determine whether the sector’s gains translate into sustained earnings improvement. Airlines weakened as fuel expenses rose, while investors assessed the risk that inflation and higher interest rates could constrain KOSPI gains. Recent buybacks by Samsung Electronics and SK Hynix and foreign net buying in September provide some downside support, although inflation data, the FOMC meeting and Middle East developments could increase volatility.