The South Korean stock market, after a period of historic gains, witnessed a dramatic downturn on Friday, May 15, as the benchmark Kospi index plunged by 6.12%. This significant drop, totaling 488.23 points, saw the index close at 7,493.18, marking its largest single-day percentage decline since March 23, 2026.
A Rally Fueled by AI Chipmakers
Prior to the crash, the Kospi index had been on a stellar bull run, surging over 185% in just one year and positioning South Korea as one of the world’s top-performing major equity markets. This remarkable growth was largely attributed to an extreme market concentration in artificial intelligence (AI)-linked chipmaker stocks, particularly Samsung Electronics Co Ltd and SK Hynix Inc.
These two semiconductor giants had seen astronomical rises in their share values over the preceding year. Samsung shares had rocketed over 375%, while SK Hynix witnessed an astonishing surge of approximately 790%. Together, these two companies commanded over 40% of the entire Kospi index weight, making the market heavily reliant on their performance.
The Sudden Plunge and Profit-Taking
The optimism, however, abruptly faded on Friday. After breaching the historic 8,000 mark and hitting an all-time intraday high of 8,046.78, a wave of selling washed over the market. Institutional and individual investors began to offload their holdings, seeking to lock in substantial profits accumulated during the rally. This profit-taking quickly snowballed into a broader market rout.
By the closing bell, the impact on the leading chipmakers was severe: Samsung Electronics had crashed 8.61%, and SK Hynix plunged 7.66%, dragging the rest of the index into the deep red.
Multiple Factors Contributed to the Sell-Off
Beyond pure valuation fatigue and the concentrated nature of the market, several other triggers accelerated the sell-off:
- Domestic Issues: Sentiment around Samsung was dented by an ongoing labor dispute, adding an additional reason for investors to reduce their exposure to the high-flying stock.
- Broader Market Weakness: Risk appetite across Asian markets was already brittle due to rising crude oil prices and escalating geopolitical uncertainty in West Asia.
- Global Economic Pressures: Compounding the tech sector's global sell-off, climbing global bond yields also put significant pressure on high-flying technology shares, making them less attractive to investors.
The May 15 crash serves as a stark reminder of the risks associated with highly concentrated market rallies, particularly those driven by a few dominant sectors or companies.