Short-sale constraints and the idiosyncratic volatility puzzle: An event study approach

Abstract

Using event studies, we show that short-sale constraints play an important role in the negative relation between idiosyncratic volatility and stock returns. We explore three exogenous events that change short-sale constraints: the IPO lockup period expiration, option introduction, and the recent short-selling ban on financial stocks. Following mitigation of short-sale constraints from the first two events, high idiosyncratic volatility stocks underperform low volatility stocks in the short and long run, and are associated with higher abnormal trading volume. Additionally, highly volatile financial firms experience greater price increases upon the short-sale ban enforcement and greater price drops upon the ban expiration.

The potential built‐in supply effect from margin trading in the Chinese stock market

“…We calculate the average margin balance of marginable stocks in China from our own data. The average margin balance in China (2.18%) and the average relative margin interest for our sample in China (5.344%) are different because the average margin balance is calculated as total debit balance scaled by total market capitalization of the marginable stocks to make it comparable to the U.S. data, while the average relative margin interest is calculated as the average of debit balance scaled by floating firm value for our sample.14 See the results on stock price efficiency (e.g.,Beber and Pagano, 2012;Boehmer and Wu, 2013;Bris et al, 2007;Chang et al, 2007;Chang et al, 2013;Chang et al, 2014;Chen et al, 2016;Choy and Zhang, 2019;Li et al, 2019), market stabilization (e.g Chang et al, 2014;Jiang et al, 2014),. market liquidity (e.g.,Beber and Pagano, 2012;Chen et al, 2016;Comerton-Forde et al, 2016;Diether et al, 2009;Marsh and Payne, 2012), analyst forecast quality(Liu et al, 2019) and manager discipline(Chang et al, 2019).…”