The Nikkei stock index soared over 2 percent Thursday as investors snapped up semiconductor-related issues on hopes for robust chip demand, with the yen’s depreciation against the U.S. dollar also lifting exporters. The 225-issue Nikkei Stock Average ended up 1,055.37 points, or 2.79 percent, from Wednesday at 38,925.63, the highest in around two months. The broader Topix index finished 70.62 points, or 2.66 percent, higher at 2,721.12. Every industry category on the top-tier Prime Market gained ground, led by miscellaneous product, metal product and electric appliance shares. The dollar remai…