Abstract: The equity pledge of the controlling shareholder of a listed company is one of the key areas of risk disposal by China's financial regulatory authorities.How to effectively restrain the controlling shareholder's irrational equity pledge is a topic worth exploring.Based on the landmark event of the implementation of margin and short selling system in China,this paper selects A-share listed companies in Shanghai and Shenzhen Stock Exchange from 2010 to 2019 as the research samples to empirically investigate whether the short selling mechanism can constrain the equity pledge of the controlling shareholders.The results show that the implementation of the short selling system can significantly inhibit the controlling shareholder's equity pledge and has high economic significance.This conclusion remains true after a series of robustness tests,such as changing key variable measures,changing sample time window,changing sample,propensity score matching,parallel trend test,and placebo test.The results of the mechanism test show that short selling pressure mainly reduces the controlling shareholder's equity pledge by improving information transparency.Finally,the heterogeneity analysis shows that the short selling pressure has a more obvious inhibiting effect on the equity pledge behavior of the controlling shareholders in the enterprise with good institutional environment,high volatility of stock price,low analyst tracking,weaknesses in internal controls and privately owned.The research conclusions enrich the research on the external governance role of short selling mechanism,but also provide evidence support for how to resolve the crisis of controlling shareholders' pledge from the source by using market-oriented means.

Key words: short selling pressure, controlling shareholder, equity pledge, information transparency