Margin trading loan balances in South Korea rose from 27.4 trillion won on August 4 to 30.87 trillion won on August 14, an increase of 3.46 trillion won, or 12.6%, in 10 days. The rebound followed an extreme KOSPI sell-off and coincided with renewed borrowing against large-cap semiconductor stocks. Samsung Electronics and SK Hynix together represented 9.69 trillion won, or 31.4%, of all margin loans on August 14. Margin loans are brokerage credit used to buy securities and can trigger margin calls, requiring investors to provide additional funds or face forced liquidation when prices fall. The KOSPI plunged 5.80% on August 19 to 6,471.17 after global long-term bond yields surged and concerns about delays to U.S. data-center construction hurt semiconductor shares. Analysts and market researchers warn that leverage can amplify both buying during rallies and selling during downturns, particularly in a market dominated by individual investors with limited hedging tools. Foreign investors switched from five consecutive sessions of net buying to a 3.5 trillion won net sale on August 19, while individual investors were the sole net buyers.