Asian markets took a sharp hit Thursday as a wave of chip-linked selling swept through the region, sending South Korea's KOSPI down as much as 7.6% and triggering a so-called sidecar curb that temporarily pauses certain computerized trades. Taiwan stocks also slipped ahead of earnings from Taiwan Semiconductor Manufacturing Co (TSMC), the world's largest contract chipmaker.
What Happened
The selloff was concentrated in the semiconductor sector, which dominates Asian equity benchmarks. In South Korea, the KOSPI's plunge was driven by heavy selling in chip stocks, particularly Samsung Electronics and memory-chip maker SK Hynix. Together, these two companies account for more than half of the index's weight, meaning their moves can quickly drag the entire market lower.
The sidecar mechanism, which halts program trading on the KOSPI for five minutes when futures drop sharply, was triggered as ETF-related selling intensified. This is the first such halt since August 2020, underscoring the severity of the move.
In Taiwan, the Taiex index fell as investors braced for TSMC's quarterly results, due later Thursday. The chipmaker's performance is closely watched as a bellwether for global semiconductor demand. For more on the broader chip selloff, see Chip Stocks Slide as TSMC Earnings Loom and Brent Crude Hits $85.45.
Why the Move Was So Big
The outsized drop highlights a structural vulnerability in Asia's tech-heavy markets. Because South Korea and Taiwan are so concentrated in semiconductor stocks, any sharp move in a few large names can cascade through the entire index. But Thursday's selloff also put the spotlight on a less obvious culprit: single-stock leveraged exchange-traded funds (ETFs).
These products promise to deliver a multiple—often two or three times—of a stock's daily return. To maintain that leverage, they must rebalance their holdings as prices move. When a stock falls sharply, leveraged ETFs are forced to sell more shares to keep their leverage ratio constant, which can amplify the decline. This mechanical selling can turn a routine profit-taking session into a rout.
South Korea's top financial regulator acknowledged the issue, saying new measures for these leveraged ETFs are coming. The move signals that authorities see the market's plumbing—not just investor sentiment—as part of the problem. For more on the regulatory response, see South Korea Plans New Curbs on Single-Stock Leveraged ETFs After KOSPI Volatility.
What It Means for Investors
For everyday investors, the KOSPI's 7.6% drop is a reminder that index moves can be exaggerated by factors unrelated to company fundamentals. When a handful of stocks dominate a benchmark, forced ETF flows can quickly turn a stock move into an index event. This raises the odds of sharp open-to-close swings and overnight gap risk in both the shares and Korea-linked funds.
If regulators clamp down on the most flow-heavy single-stock leveraged products, that could reduce some mechanical volatility. But it may also shift trading into other vehicles or reduce liquidity in the same two stocks that set the tone for the broader market. Investors holding Korea-focused ETFs or individual chip stocks should be aware that these dynamics can persist even after the current selloff fades.
The broader context also matters. The selloff comes amid a mixed backdrop for Asian markets. Earlier this week, Japan Earnings Deliver Mixed Results: Consulting Stocks Surge, Renewables Slide, while Indian Stocks Edge Up as IT Rebounds; Oil Stays Near $85 on Iran Strikes. Meanwhile, the Bank of Korea recently hiked rates to 2.75%, adding to headwinds for the Korean economy.
Looking Ahead
All eyes are now on TSMC's earnings, which could set the tone for global chip stocks in the coming days. A strong report might calm nerves, but any disappointment could reignite selling. For now, the sidecar halt has given Korean markets a brief breather, but the underlying pressures—from ETF rebalancing to regulatory uncertainty—remain.
Investors should watch for further announcements from South Korean regulators and monitor TSMC's outlook for signs of demand trends in the semiconductor industry. The episode underscores how quickly market structure can turn a routine selloff into a dramatic event, and why understanding the mechanics behind the moves is just as important as the headlines.
