Tokyo stocks fell Monday morning on jitters after a US credit rating downgrade over the weekend, while the Group of Seven financial leaders'' bid to stabilize financial markets was seen as lending some support. The 225-issue Nikkei Stock Average lost 121.85 points, or 1.31%, from Friday to 9,178.03. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 13.29 points, or 1.66%, to 787.67. All 33 sectors on the TSE weakened, with the electricity and gas sector leading decliners, followed by the real estate and metal products sectors, according to Japan''s (Kyodo) news agency. Stocks tumbled at the outset of trading, brushing aside better-than-expected July US employment data released Friday, as players were discouraged by Standard & Poor''s slashing of the US credit rating for the first time, brokers said. But following the initial falls, stocks traded narrowly after the G-7 financial leaders released a joint statement in the morning that stressed their commitment to stabilizing global financial markets in the wake of debt problems in the United States and Europe. Brokers said once the yen''s strength against the US dollar eases, it would take some pressure off export-oriented issues in Tokyo. The dollar was in the lower 78 yen range during the morning session of stock trading after temporarily dropping to the upper 77 yen level earlier.