Nearly 4 out of 10 listed units of South Korea's top 10 conglomerates saw their sales drop in the first half of 2016 from a year earlier due mainly to falling exports, data showed Thursday.

According to the data by the Korea Exchange, 26 out of 68 listed affiliates of the 10 largest family-controlled conglomerates, or 38 percent, suffered on-year falls in revenue for the January-June period. 

Those underperformers include leading steelmaker POSCO, major shipbuilder Hyundai Heavy Industries Co., chip giant SK hynix Inc., top mobile carrier SK Telecom and home appliance giant LG Electronics Inc.

The 68 companies, which are traded either on the main bourse or on the secondary KOSDAQ market, close their books in December.

The data also showed the companies' combined sales standing at 496.2 trillion won ($448 billion) in the six-month period, up a mere 0.28 percent from the same period a year earlier.

The growth rate was lower than a 0.64 percent on-year increase for all firms listed on the main bourse and a 4.33 percent expansion for the KOSDAQ-registered companies.

Excluding tech behemoth Samsung Electronics Co., the total revenue of the top 10 groups' listed companies shrank 0.93 percent in the first half from a year earlier. First-half sales of Samsung Electronics came to 100.7 trillion won, compared with 95.7 trillion won a year ago.

According to the data, five of the 10 leading conglomerates saw their first-half sales decline from a year earlier. SK Group, South Korea's third-largest conglomerate, posted the largest drop of 6.8 trillion won, followed by POSCO with 6.6 trillion won and Hyundai Heavy Industries with 4.1 trillion won.

Experts cited South Korea's plunging exports as the main culprit for their sales drop. South Korea's exports fell 10.2 percent on-year in July, marking a record 19th straight month of decline.

Analysts painted a gloomy picture of the listed firms' sales growth in the second half.

"It is tough to expect a rise in their revenues for the July-December period, given the strong local currency and other unfavorable factors," said Yoo Seung-min, chief investment strategist at Samsung Securities Co. (Yonhap)