South Korea's 10 biggest business conglomerates saw their combined market cap fall 40 trillion won($34 billion) from the beginning of the year as their share prices tumbled on earnings concerns, market data showed Sunday.

The business groups' market cap totaled 679.6 trillion won as of July 23, falling 40.1 trillion won, or 5.57 percent from Jan. 2, the first trading day of the year, according to the data by market tracker Chaebul.com.

The portion of their market cap also dropped by 8.3 percentage points in the cited period to 45.22 percent.

By group, Hyundai Motor Group, the country's biggest automotive group, suffered the biggest fall, with its market cap plunging by 22.1 trillion won to 98.8 trillion won.

The move lowered the combined portion of the group's listed affiliates, such as Hyundai Motor, Kia Motors and Hyundai Mobis, to 6.56 percent from 8.99 percent.

Samsung, the country's biggest business group, also weathered a substantial fall in its market cap. The combined market cap of listed Samsung affiliates slumped by 21.9 trillion won to 327.7 trillion won.

Their portion, which accounted for more than one-fourth of the stock market earlier this year, also slipped to 21.79 percent, according to the data.

Steel heavyweight POSCO, which has been mired in corruption charges as well as sluggish earnings, also saw the market cap of its affiliates drop 8.9 trillion won to 21.4 trillion won.

In contrast, Hanwha saw the combined market cap of its affiliates rise by 4.8 trillion won to 18.4 trillion won. Lotte, GS, LG and Hanjin were also among the conglomerates that saw their market cap increase.

The data comes as large caps that trade on the Korea Composite Stock Price Index, the country's key stock market, saw their share prices fall this year. Most of the decliners were companies in the tech, auto and steel industries. (Yonhap)