中文摘要：

2014—2015年，我国股市大涨大跌引起了人们对融资融券是否加剧股市波动的争议。本文基于我国融资融券业务试点及逐步扩容的准自然实验，运用双重差分模型和倾向得分匹配法，研究融资融券对股价波动性的影响。结果表明：融资融券显著降低了标的股票的股价波动幅度、收益率波动性和股价跳跃风险，在平抑股价异常波动方面的作用最为显著；融资融券在股市剧烈波动时期没有助涨助跌，其平抑股价波动的效果反而比股市平稳震荡时期更加明显。

英文摘要：

The violent fluctuations of China＇ s stock market in 2014-2015 give rise to the controversy of whether or not margin trading aggravates stock price volatility. Basing on the natural experiment of the establishment and expansion of China＇s mar- gin trading system, this paper uses EGARCH model and propensity score matching to investigate the impact of margin trading on stock volatility. The empirical tests show that margin trading significantly reduces the fluctuation amplitude of stock price, returns volatility and price jump risk, and its stabilizing effect on abnormal fluctuations is particularly prominent. Margin trad- ing can significantly reduce stock volatility even under the unfavorable market condition of violent fluctuations.