The Nikkei stock index extended its losses to a nearly two-month intraday low Tuesday morning, briefly dropping over 2 percent after an overnight plunge on Wall Street and on concern over the impact of China’s stringent COVID-19 restrictions on the global economy. At 10 a.m., the 225-issue Nikkei Stock Average fell 507.64 points, or 1.93 percent, from Monday to 25,811.70. The broader Topix index was down 34.63 points, or 1.84 percent, at 1,843.76. The benchmark Nikkei fell below the 26,000 line for the first time since March 16.