Tokyo stocks tumbled Monday with selling led by semiconductor heavyweights tracking falls in their U.S. counterparts and exporters hurt by a stronger yen. The 225-issue Nikkei Stock Average ended down 868.45 points, or 2.19 percent, from Friday at 38,820.49, its largest single-day point drop since June 2021. The broader Topix index finished 59.97 points, or 2.20 percent, lower at 2,666.83. On the top-tier Prime Market, decliners were led by mining, bank and securities house issues. The U.S. dollar traded around the 147 yen line after briefly dropping to the mid-146 yen range in Tokyo on yen bu…