In 2018, the combined sales of non-financial firms here rose 4 percent from the year before when the comparative figure jumped 9.2 percent on-year, according to the report from the Bank of Korea.
Their average operating profit to sales ratio slipped to 5.6 percent from 6.1 percent over the cited period, with their net profit to sales ratio also dipping to 5.3 percent from 6.1 percent.
The annual report is based on financial statements submitted by nearly 670,000 local companies to the tax agency that include some 150,000 manufacturing firms.
The combined sales of manufacturing companies grew 4 percent in 2018, slowing from a 9 percent on-year increase in the previous year, while those of non-manufacturing firms grew at the same pace, slowing from a 9.3 percent rise in 2017.
The combined sales of large companies increased 2.7 percent on-year, while those of smaller firms rose 5.9 percent. Both figures mark a sharp slowdown from 7.9 percent and 11.0 percent on-year increases, respectively, in the year before, according to the report.
Such a sharp drop in sales of local companies apparently indicates the start of various problems still facing the local companies, including a global downturn that has kept the country's outbound shipments shrinking for 11 consecutive months.
The country's exports reached an all-time high of over $605 billion last year but have been on a steady decline since December.
The report also showed the persistent slump in the global semiconductor market may have begun in 2018.
The rise in the combined sales of electronics and communication device producers here slowed to 3.4 percent in 2018 from a 20.4 percent on-year spike the previous year.
Electronics and communication devices, such as semiconductors and smartphones, make up more than one-quarter of South Korea's overall exports.
In the first nine months of 2019, exports of semiconductors tumbled 25.3 percent on-year to $71.4 billion from $126.7 billion over the same period last year, according to an earlier report.
Despite the slowing growth in their sales, the financial health of local companies improved from a year earlier in 2018, with their debt to equity ratio falling to 111.1 percent from 114.1 percent.
By sector, the average debt ratio of manufacturers slipped to 73.6 percent from 77.0 percent, while that of non-manufacturing firms also dropped to 149.2 percent from 151.7 percent. (Yonhap)