The KOSPI Bubble

The KOSPI has rocketed 88% in 2026 and 200% over two years, transforming South Korea's benchmark into a concentrated semiconductor play. Samsung Electronics and SK Hynix now represent nearly 60% of the index, creating what Goldman Sachs flags as a structural risk for foreign institutions bound by diversification mandates.

Goldman warns that a single percentage point increase in the combined weight of the two chipmakers could trigger forced selling by foreign institutional investors constrained by portfolio allocation rules. The concentration has effectively turned the KOSPI into a proxy for global AI infrastructure spending rather than a diversified reflection of South Korea's domestic economy.

The rally mirrors the chip sector's dominance in AI buildout, but the regulatory threshold creates a binary risk: further outperformance by Samsung and SK Hynix could paradoxically force institutional liquidation regardless of fundamentals. The index's fate is now tied to two names navigating both AI demand cycles and weight-ceiling mechanics that could cap foreign inflows.