The Nikkei 225 has plummeted, with reports of the decline ranging from over 1,900 points to over 4,000 points in two days, amid a selloff in ai and semiconductor stocks. The drop has been attributed to a semiconductor-led selloff, with some outlets citing a risk-off wave triggered by us and south korea semiconductor selloff. The index has fallen below various reported levels, including 66,000 and 65,000, with the exact extent of the decline unclear.