AI-related trades push Japan stock volatility to 18-year high

Japan’s stock market has entered its most volatile period since the 2008 global financial crisis, as trading concentrated in artificial intelligence-related shares amplifies movements across the broader market. The Nikkei Stock Average fell 3% on Aug. 19, highlighting the scale of recent fluctuations. The decline came amid continued investor focus on artificial intelligence trades and uncertainty surrounding the chip sector. Margin trading is expected to fuel further volatility. Borrowed funds can magnify gains and losses, potentially prompting sharper position adjustments when prices move rapidly. That dynamic may intensify selling pressure during declines and accelerate rebounds when sentiment improves. The concentration of trading in artificial intelligence and related chip stocks also leaves the wider Japanese market more sensitive to changes in expectations. Positive developments can support strong gains, but disappointing news or shifting investor sentiment may produce broader and faster declines. Investors will be watching whether artificial intelligence-related activity continues to dominate trading and whether uncertainty in the chip sector generates additional instability. With margin positioning adding to market sensitivity, further fluctuations are expected. The developments underscore the risks of powerful, concentrated market themes. Artificial intelligence remains central to trading activity, while chip-sector uncertainty and leveraged positioning are increasing the responsiveness of Japanese equities to sentiment changes. The report was published Aug. 20, 2026, at 00:49 JST. The content was commissioned by Nikkei’s Global Business Bureau.