Nine out of South Korea's top 10 family-controlled conglomerates saw their stock market capitalizations plunge this year due to weak earnings stemming from a prolonged economic slump, data showed Sunday.

The combined market value of the 90 listed companies belonging to the 10 biggest conglomerates, known as chaebol, came to 630.9 trillion won (US$567 billion) as of Friday, down 9.4 percent from the beginning of this year, according to the data by financial information provider FnGuide.

During the same period, the KOSPI, the benchmark index of the country's main stock market, dropped 7.9 percent.

SK Group, the country's third-largest conglomerate, was the only one that posted a gain in market value with the figure edging up 1.2 percent to 70.6 trillion won.

Samsung Group, which has global tech giant Samsung Electronics Co. under its wing, suffered the biggest decline in market capitalization. During the cited period, Samsung's market value tumbled by 46 trillion won, or 14.1 percent, to 281.1 trillion won.

The drop was attributed to the weak performance of Samsung Electronics, whose market value nosedived to 190.8 trillion won as of Friday from 232.1 trillion won at the start of the year.

Hanjin Group, whose flagship is South Korea's top air carrier Korean Air Lines Co., saw its market capitalization drop 33.6 percent to 36.5 trillion won over the cited period.

The market capitalization of Hyundai Motor Group, South Korea's No. 2 conglomerate, fell 1.6 percent to 128.7 trillion won during the period, but their two core affiliates -- Hyundai Motor Co. and Kia Motors Corp. -- saw their market value rise 5.8 percent and 11.2 percent each on expectations of continued sales growth amid a recovery in the U.S. and other advanced economies.

Of the 90 companies, 59 suffered declines in their market capitalization during the cited period with the remainder posting increases, according to the data. (Yonhap news)