This paper explores the determinants of B-share discounts in the Chinese stock market based on a unique regulatory change in 2001. We find that the B-share discounts declined substantially after the lifting of restrictions on foreign ownership in China, but the H-share discount remained virtually unchanged. Using the intraday data, we find that information flows from the B-share markets to the A-share markets increase significantly after the event, because domestic investors rush into the B-share markets. Using various cross-sectional analyses, we also find that relative supply and behavior factors such as relative spread (or liquidity) and relative risk affect the discounts throughout the sample period.