Goldman says each 1-point rise in the chipmakers’ combined KOSPI weight could trigger about $2 billion in foreign outflows, as leveraged ETF, options and margin activity heighten concentration risks.
An AI-driven rally in Samsung Electronics and SK Hynix has lifted their combined weighting in South Korea’s KOSPI to a record 60%, up from about 40% two years ago, deepening concern over concentration in the benchmark index. Goldman Sachs analysts Timothy Moe and John Kwon said on June 30 that every 1 percentage point increase in the pair’s combined index weighting could lead to roughly $2 billion in foreign outflows because U.S. Investment Company Act diversification rules can force portfolio rebalancing. The concern has intensified after regulators twice halted KOSPI trading during a sharp drop last week and delayed plans for large-cap options including SK Hynix, while Goldman also flagged leveraged ETF inflows, rising options activity and margin retail trading as factors that could amplify swings and forced selling beyond fundamentals.