The Nikkei stock index surged over 2 percent early Friday as stronger-than-expected U.S. retail sales figures eased concerns about a recession striking the world’s largest economy, while a weaker yen lifted exporters. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 884.85 points, or 2.41 percent, from Thursday to 37,611.49. The broader Topix index was up 54.11 points, or 2.08 percent, at 2,654.86. Every industry category on the top-tier Prime Market gained ground, except for farm and fishery issues. Gainers were led by bank and nonferrous metal issues.