TOKYO, Sept. 8 — A violent swing in the yen tore through Japanese equities on Monday, with the Nikkei 225 dropping 1,130 points to give back much of the previous session’s 1,378-point AI-driven rally. The broader TOPIX index fell 75.47 points, or 1.83%, closing at 4,050.33, as a currency shock overrode the market’s recent resilience. The trigger was a sharp surge in the yen, which climbed as high as the 153 range against the dollar — its strongest level since February 18.
Traders unwound short-yen and carry-trade positions as markets priced in faster Bank of Japan tightening, supported by stronger wage data and an upward revision to Japan’s April-June economic growth. Exporters bear the brunt A stronger yen reduces imported inflation pressure for households, but it hurts exporters by lowering the yen value of overseas earnings. That dynamic punished automakers such as Toyota and Honda, which had benefited when the dollar sat near 160 yen.
Machinery, electronic-component and precision-instrument makers with large overseas sales also came under pressure. The speed of the move mattered as much as its direction. After months of weak-yen earnings expectations had propped up Japanese equities, the rapid appreciation forced investors to rebalance in a hurry.
The sell-off was broad, reaching beyond high-priced technology shares into financials, exporters and other sectors sensitive to currency and interest-rate moves. Notably, the TOPIX, which had often outperformed the Nikkei during periods of AI and semiconductor volatility, saw its recent resilience snap. AI names lose their shield Monday’s action also shifted the policy narrative.
Previously, markets had focused on the possibility of Japanese intervention to stop the yen from weakening beyond 160. Now, attention turned to whether rapid yen strength could become a fresh headwind for exporters and overall equity sentiment. The September 7 rally had been powered by AI and semiconductor names, with SoftBank Group, Advantest and Tokyo Electron accounting for much of the Nikkei’s gain.
On Monday, investors were far less willing to chase those names as the yen surge and a global risk-off tone took control. Advantest, a major index driver with direct exposure to advanced chip testing, remains one of Japan’s clearest beneficiaries of AI semiconductor demand — but it is highly sensitive to rising interest-rate expectations and shifts in global risk appetite. Tokyo Electron, central to Japan’s role in the global chip supply chain, is vulnerable whenever investors question whether AI-related capital spending can continue.
Other closely watched stocks included Kioxia Holdings, Fujikura, Furukawa Electric, Ibiden, Renesas Electronics, Rohm, Lasertec and Kokusai Electric. The day’s broad decline underscored a simple lesson: even strong long-term AI demand cannot fully shield the market from currency and rate shocks.
What to watch next is whether the yen’s climb extends or stalls. If the currency keeps firming, the pressure on exporter earnings and equity valuations will only intensify. If it stabilises, the question becomes whether AI enthusiasm can reassert itself in a market now acutely aware of its currency exposure.
