Tokyo stocks fell back Thursday, with the Nikkei Stock Average sliding 121.07 points, or 1.19%, to end the day at 10,039.33. The benchmark index’s rise the previous day to above 10,000 for the first time in about eight and a half months, combined with Wall Street’s losses overnight, prompted investors to lock in gains, according to (Nikkei) website. The Nikkei average briefly widened its losses in mid-afternoon trade due in part to the dollar’s weakening to the 83 yen level. The Bank of Japan decided to further ease its monetary measures at its two-day policy board meeting that began Wednesday. Buying momentum was not strong enough to push the Nikkei Stock Average upward, as the move had already been factored in.