Nextrade (NXT) will introduce a static volatility interruption in the premarket to prevent sharp price swings caused by small orders. It will also change the post-trigger process from a temporary trading halt to a call auction that collects orders to set a price. Nextrade said it revised its rules and will implement the changes from Sept. 14. The move follows recent cases of limit-up or limit-down trades on small volumes.

Kiwoom Securities said its retail client base topped 9.05 million as of end-July, up about 920,000, or 11 percent, from a year earlier. It said growth among high-net-worth clients was steeper, with clients holding 1 billion won or more in deposited assets up 80.7 percent and those with 3 billion won or more up about 90 percent. Top holdings shifted toward large-cap semiconductor and auto stocks including Samsung Electronics, SK Hynix and Hyundai Motor, with preferences varying by age.