TOKYO, Dec. 6 (Xinhua) — Tokyo stocks opened lower Thursday as investor sentiment was dampened by European shares retreating overnight as global bourses react to concerns over the future course of the U.S. economy.

As of 9:15 a.m., the 225-issue Nikkei Stock Average dropped 233.39 points, or 1.06 percent, from Wednesday to 21,685.94.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 15.01 points, or 0.91 percent, at 1,625.48.

Metal product, machinery and iron and steel-linked issues comprised those that declined the most in the opening minutes after the morning bell.