On November 5, Japanese and South Korean stock markets tumbled sharply amid concerns over AI regulation. The Nikkei 225 Index closed down 1,110.73 points, or 1.79%, at 61,077.90, while South Korea's KOSPI Index closed down 300.15 points, or 5.28%, at 5,383.65. The KOSDAQ fell 5.11%. Sidecar mechanisms were triggered successively during intraday trading, temporarily halting program trading. Among individual stocks, SK Hynix dropped 9.45% and Samsung Electronics fell 7.56%.