TOKYO, Sept. 18 (Xinhua) -- Japan's benchmark Nikkei stock index was essentially flat Wednesday morning as investors were in a wait-and-see-mood ahead of the outcome of the U.S. Federal Reserve's two-day policy-setting meeting later in the day.

The 225-issue Nikkei Stock Average edged up 11.40 points, or 0.05 percent, from Tuesday to 22,012.72.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, lost 6.50 points, or 0.40 percent, at 1,608.08.

Marine transportation and miscellaneous product stocks led notable advancers, while mining, and oil and coal product-linked issues comprised those that declined the most by the morning break.