The Nikkei 225 has plummeted, with reports indicating a drop of around 1,900 points, although the exact figure varies. The decline is attributed to a selloff in semiconductor and AI stocks, with some outlets citing a rout in South Korea's KOSPI and a slump in US semiconductor stocks as contributing factors. The plunge has erased the previous day's gains, with the index briefly nearing a significant threshold, although the exact level is not consistently reported.