Tokyo stocks opened sharply lower Wednesday, with the Nikkei index sinking over 3 percent, on renewed concerns about the U.S. economy following the overnight release of weaker-than-expected U.S. manufacturing data. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 1,199.76 points, or 3.10 percent, from Tuesday to 37,486.55. The broader Topix index was down 73.23 points, or 2.68 percent, at 2,660.04. Every industry category on the top-tier Prime Market lost ground, led by mining, oil and coal product, and nonferrous metal issues.