Stock market openness and market quality: evidence from the Shanghai-Hong Kong stock connect program

We study the impact of capital market openness on high-frequency market quality in China. The Shanghai–Hong Kong Stock Connect program (SHHKConnect) opens China's stock market to foreign investors and offers a natural experiment to investigate this question. Using a difference-in-differences approach, we find that market liberalization leads to lower quoted spread, lower effective spread, lower market depth, and higher short-term volatility. Our findings imply that opening the markets to more sophisticated foreign investors is associated with higher competition and more cross-market arbitrage activities, narrowing the spread and reducing liquidity providers’ profits, but increasing the price impact and short-term volatility of connected stocks.