The Financial Supervisory Service and Korea Exchange have embarked on a joint investigation into alleged manipulation of stocks connected to politicians and well-known figures.

A group of retail investors has been chasing so-called “celebrity stocks” related to politicians and famous figures without taking the shares’ true value into consideration.

The celebrity stocks include those tied to Rep. Park Geun-hye, former chairwoman of the governing Grand National Party, and Moon Jae-in, a rising presidential candidate among opposition parties.

Stocks of Ahnlab Inc., a software firm founded by Ahn Cheol-soo, zigzagged over whether Ahn would run or not for Seoul mayor.

The stock price of the company fell by the daily limit to 40,750 won ($38) on the Korea Exchange Wednesday morning, a day after Ahn pledged not to run and instead threw his support behind leading liberal activist Park Won-soon.

Last week, Ahn, who had been widely favored for the post, had seen the company’s stock gain more than 35 percent as investors clamored for shares on speculation that the firm would benefit if he ran.

Ahn held a 37.1 percent stake in the company at the end of June.

Shares of Pulmuone Holdings Co., where Park Won-soon serves as an outside director, jumped more than 11 percent after Ahn’s announcement.

A Korea Exchange official said the main bourse and the FSS are looking into sudden rises in shares to prevent cases of stock price manipulation.

“Ahn Cheol-soo-related shares have risen sharply in recent sessions. We are monitoring such shares on a daily basis,” he said.

“If we feel that a certain group of investors is attempting to manipulate stock prices, we will step up our investigation,” he said.

Research analysts said that the celebrity effect could be a vehicle for speculative movements on the stock market.

In contrast to retail investors’ high interest, some market watchers have stayed cool about the sudden surge in those shares.

No local brokerages have issued reports on Ahnlab, with the exception of small published notes that speculate the recent surge in the venture firm’s shares was likely due to Ahn’s possible emergence as a Seoul mayoral candidate.

FSS officials say the abnormal movement of such shares in South Korea is much more volatile compared to that of other countries. Although Korea is stepping up education for investors, the issue is difficult to tackle.

An FSS offical said that price jumps in celebrity shares tend to last for a short time rather than a few weeks and that investors need a prudent approach in purchasing such shares.

By Kim Yon-se (kys@heraldcorp.com)