by Xie Yu HONG KONG (Reuters) – Asian shares fell whereas US Treasury yields fell on Wednesday after score company Fitch Rankings unexpectedly downgraded the USA’ sovereign credit standing. MSCI’s broadest index of Asia-Pacific shares fell 0.5%. Japan’s Nikkei fell 1.2%, whereas Australian shares fell 0.5%. Mainland China and Hong Kong fell 0.3% and 0.5%, respectively. Asian shares had been additionally affected by declines on Wall Road in a single day. US inventory futures, the S&P 500 e-minis, fell 0.2% on Wednesday. Fitch Rankings downgraded the US by one notch to AA+ from AAA, citing the monetary deterioration, a call