South Korea's semiconductor heavyweights suffered another sharp selloff on Thursday, erasing the previous session's rebound and underscoring how leveraged positioning has turned the country's artificial-intelligence trade into a high-volatility affair. SK Hynix tumbled 6.95%, Samsung Electronics dropped 2.44%, and the benchmark Kospi index fell 3.64%, a stark reversal from Wednesday's gains of roughly 6%, 3%, and 4%, respectively.
The latest decline came despite no deterioration in the companies' earnings outlook. Instead, the trigger was a shift in global technology sentiment, illustrating how leverage, short positioning, and crowded AI trades can transform ordinary mood swings into outsized daily moves. Wall Street's weakness, where the Nasdaq snapped its winning streak after SpaceX and AMD fell following earnings, set the tone. AMD beat analyst forecasts but failed to meet the high expectations already priced into its valuation. SpaceX exceeded revenue estimates, yet investors worried about the sustainability of profitable Starlink operations funding costly data-center and AI expansion.
The weakness quickly spread across Asian tech markets. In Tokyo, Kioxia plunged 9.61%, and chip-equipment maker Tokyo Electron lost 4.61%, suggesting Thursday's retreat was not company-specific but sector-wide. The reversal was particularly striking because memory stocks had received a bullish signal just a day earlier when SpaceX CEO Elon Musk said "the limiting factor currently is memory," arguing that supply growth lagged AI-related demand.
Korea's semiconductor boom has attracted leveraged retail investors and concentrated institutional positions. When prices fell in July, margin calls and daily rebalancing by leveraged exchange-traded funds forced additional selling. Charu Chanana, Saxo's chief investment strategist, noted that leverage amplifies losses and increases forced-sale risks during market stress, adding that powerful themes can become "crowded, expensive and vulnerable to corrections."
Goldman Sachs estimates that assets in Korean leveraged ETFs have fallen from a June peak of $53 billion to $25 billion. Retail margin-loan balances declined from $25 billion to $19 billion, indicating substantial deleveraging has occurred without eliminating instability. The mechanism works in both directions. Citi analyst David Chew told MarketWatch that Korean short positioning had become sufficiently one-sided for stabilizing AI sentiment to trigger a short-covering rally, explaining Wednesday's surge and Thursday's fall. Leveraged selling accelerates weakness, while short covering magnifies rebounds—neither necessarily signals next quarter's demand for high-bandwidth memory.
Strong fundamentals are no longer enough to calm investors. Goldman Sachs remains bullish on the cycle, writing that memory demand is likely to be "stronger and last longer than previous ones," supported by accelerating AI computing and shortages that could persist through 2030. The bank nevertheless acknowledged concerns about Big Tech capital spending, financing risks, and competition. Investors are questioning whether customers can maintain current expenditure levels and whether expanding production will eventually weaken pricing.
Samsung and SK Hynix have signaled plans to strengthen shareholder returns after reporting record quarterly profits. Those commitments may support valuations, but Thursday's decline showed that dividends and buybacks offer limited protection when global AI sentiment turns. The recent memory demand warning from Musk had fueled optimism, but the market's reaction highlights the fragility of the current rally. For investors, the key takeaway is that Korea's AI boom has become a volatility machine, where daily swings are amplified by leverage and crowded positioning, making it essential to monitor not just fundamentals but also market structure.
As the sector continues to experience sharp reversals, some analysts point to the lingering leverage hangover as a persistent risk. The Kospi's 4% drop earlier this month and the subsequent rebound illustrate the pattern. While the long-term AI demand story remains intact, the path is likely to remain bumpy. Investors should brace for continued volatility as the market digests the interplay between strong fundamentals and fragile sentiment.
This article is for informational purposes only and does not constitute financial advice.
