The B-share markets in China, originally for foreign investors only, were opened to local investors in 2001. This reform was expected to improve the information efficiency in B-share markets, since local investors were supposed to be better informed than foreign investors. Meanwhile, we find that, after opening to local investors, B-share price synchronicity increases, and firm-specific return variation (idiosyncratic risk) decreases. Opening B-share markets to local investors fails to improve or even deteriorates the information capitalization of B-share prices. The findings may help us understand Chinese government’s policy making. For instance, in August 2007, Chinese government announced that Chinese citizens would be allowed in public to buy and sell Hong Kong stocks through special accounts with domestic commercial banks. But after hearing opinions from different entities, Chinese government decides to infinitely postpone this policy.