TOKYO, July 4 (Xinhua) -- Tokyo stocks opened lower Wednesday as the market mood was dented following Wall Street's overnight retreat as ongoing U.S.-triggered trade tensions saw investors risk averse.

As of 9:15 a.m., the 225-issue Nikkei Stock Average dropped 108.12 points, or 0.50 percent, from Tuesday to 21,677.42.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 4.56 points, or 0.27 percent, at 1,688.24.

Service, electric appliance and precision instrument-oriented issues comprised those that declined the most in the opening minutes after the morning bell.