PHOTO: BLOOMBERG[SEOUL] Investing in South Korea’s stock market has yielded huge returns this year, but it has been a wild ride. Here are some reasons for the unprecedented volatility in South Korean stocks. Asean Intelligence Get insights into businesses across South-east Asia Get the free reportThe Samsung-SK Hynix phenomenonTwo companies account for South Korea’s roller-coaster stock performance: Samsung Electronics and SK Hynix. When South Korean stocks lurched lower in late July, Finance Minister Koo Yun-cheol acknowledged that authorities should have examined the products more carefully before their launch. By the end of July, the amount of stock buying using borrowed money had eased from a June peak, after stock losses led to forced selling and a retreat from South Korean ETFs.