South Korea's bourse operator said Friday it has launched a probe into the trading of Doosan Group shares over possible unfair practices after they surged right before the announcement of the new chief.

At around 2:40 p.m. on Wednesday, the country's power equipment and construction conglomerate said Park Jeong-won, chairman of the group's de facto holding firm Doosan Corp., was designated to be the group's new chairman to replace Park Yong-maan.

In the late morning trades of the day, Doosan shares had already advanced more than 2 percent, and they rose even further to finish at 5,900 won, a 7.82 percent increase from the previous session.

The following day, Doosan advanced 3.08 percent, with shares of other affiliates, including Doosan Heavy Industries & Construction Co. and Doosan Infracore Co., also trading bullish this week.

"We've spotted unusual movements in the trading of Doosan shares, where the prices and the trade volume grew sharply just hours before the official announcement of the succession," an official from the Market Oversight Commission of the Korea Exchange said.

After looking into the chances of any unfair trading by exploiting undisclosed information, the official said the KRX will send the case to the Financial Services Commission for further inspection or any punishable measures if needed.

Doosan officials, however, dismissed such chances, pointing to Doosan Infracore's recent move regarding the sale of its machine tool business unit as a reason for the recent spike.

As of 10:00 a.m. on Friday, the Doosan Group fell 0.72 percent to 83,200 won, Doosan Infracore advanced 2.79 percent and Doosan Heavy went up 2.62 percent. 

Jeong-won, the eldest son of former Doosan Group Chairman Park Yong-kon and also one of Yong-maan's nephews, had been rumored to be the next to take the helm of the business group. His inauguration will usher in the fourth generation of family management for the conglomerate.(Yonhap)