The use of undisclosed information accounted for the largest share of 112 unfair trading practice cases caught by South Korea’s sole bourse operator last year.

According to the Korea Exchange on Sunday, the number of suspicious cases reduced by eight from 2019, but several different types of market disturbances took place in the local stock market.

About 79.5 percent of unfair trading cases occurred on the tech-heavy Kosdaq market, followed by 17 percent on the main bourse Kospi market and 3.5 percent on other markets, including the third-tier Konex market, the data showed.

Nearly half the illegal trading was conducted by using undisclosed information, marking 47.5 percent of the total. Some unlawful traders avoided losses and generated unfair profits through listed firms’ unreleased information such as delisting risks and COVID-19 vaccine developments.

Backed by advancement of the bourse operator’s market surveillance system, the number of stock price manipulation cases jumped 65 percent on-year to 33, the officials said. Some fraudulent stock transactions via social networking services were also captured.

The KRX is set to reinforce the market analysis system within this year to cope with diversified unfair trading. It will pay keen attention to the illegal usage of undisclosed information and transactions of themed-stocks related to the presidential election and biopharmaceuticals. If unfair trading is detected, the cases will be reported to the Financial Services Commission, officials explained.

By Jie Ye-eun (yeeun@heraldcorp.com)