Narrow Results

As the most influential regulation in 2016, China launched circuit breakers in the financial markets. However, the circuit breaker mechanism was implemented for only four days and then suspended. Many criticisms then stated that circuit breakers impeded trading behavior in Chinese financial markets. This study explores this short-life circuit breaker mechanism in China, and examines whether circuit breakers impede trading behavior in Chinese financial markets as many criticisms stated. We use an intraday dataset and investigate the circuit breakers. Contrary to those criticisms, we find that circuit breakers are not easily reachable and have no “magnet effect” between two thresholds of breakers. We also find that without protection of circuit breakers, potential large market fluctuations will have negative impacts on individual stocks’ liquidity and value. As the major contribution, our study indicates that Chinese financial markets still need a circuit breaker mechanism to protect investors’ benefits and maintain the market liquidity and stability.

This paper uses transaction data to estimate how single stock circuit breakers on the London Stock Exchange affect other stocks that remain in continuous trading. This “spillover” effect is estimated by calculating the effect of a trading halt on the market quality of stocks that remain in continuous trading and comparing this with the effect of a stock whose absolute returns are of a magnitude nearly sufficient to trigger a trading halt but do not do so. Market quality is measured using a combination of trading costs, volatility and volume. In the two-month period we study, characterized by a relatively volatile trading environment, we find that circuit breakers lead to a significant improvement in the liquidity, and reduction in the volatility, of stocks that remain in continuous trading. This suggests that — at least over the period covered by our data — single stock circuit breakers can play an important role in reducing the spillover of poor market quality across stocks.