The consolidated operating margin of SK hynix, the crown jewel of South Korea's No. 3 conglomerate SK Group, came to 45.6 percent during the April-June period, the largest among the top 30 listed companies by market capitalization, according to the data by the Financial Supervisory Service.
KT&G Corp., South Korea's leading tobacco producer, came next with a figure of 33.3 percent, trailed by Naver, which runs the country's largest internet portal, with 25.3 percent.
Top-cap and global tech behemoth Samsung Electronics Co. came fourth with 23.1 percent, followed by Shinhan Financial Group Co. with 19.4 percent.
The figure refers to the ratio of operating income to sales and serves as a key barometer of a company's profitability.
Analysts attributed SK hynix's stellar performance to a global boom in the semiconductor business stemming from rising demand.
The second-quarter operating margin of Samsung Electronics represented an all-time quarterly high for the tech goliath. Samsung's chip business posted an operating profit of 8.03 trillion won in the quarter, compared to 2.64 trillion won posted a year earlier.
KT&G also chalked up a high operating margin thanks to increased exports and no marketing expenses. The company is banned from spending on marketing activity because of its market dominance.
In contrast, automakers, oil refiners and cosmetics companies saw their operating margins dropping in the second quarter from a year earlier due to China's economic sanctions over South Korea's deployment of an advanced US missile defense system and falling oil prices.
The operating margin of No. 1 automaker Hyundai Motor Co. came to 5.5 percent in the second quarter, compared to 7.1 percent a year ago. AmorePacific Corp., the country's top cosmetics maker, saw its figure tumble from 16.7 percent to 8.4 percent over the cited period.
Hyundai Motor, its smaller sister Kia Motors Corp. and AmorePacific were among South Korean companies hit hardest by China's economic retaliation for the deployment of a Terminal High Altitude Area Defense, which Beijing suspects could be used to spy on its military.
Industry leader SK Innovation Co. and other oil refiners suffered setbacks in their operating margins due to a downturn in international crude prices, according to market watchers. (Yonhap)