In 2019, Chinese stock market regulators launched a comprehensive reform of the IPO regulatory system, transitioning from the approval system to the registration system. Using this reform as a quasi-natural experiment, we investigate the impact of IPO systems on market manipulation. We find that the registration system reform significantly inhibits market manipulation by improving the quality of firms’ information supply and reducing stock information asymmetry. In addition, our results indicate that the inhibitory effect of the registration system reform on market manipulation is more pronounced for firms with higher information exposure, greater information complexity, and a greater proportion of investors with better ability to interpret information. Further analyses show that the registration system reform also lowers trading values around manipulation events, and inhibits other types of trade-based manipulation and misconduct. This study sheds light on the crucial role of information transparency in financial markets’ effectiveness and investor protection.

This study investigates the impact of heightened investor attention on stock price manipulation. To establish causality, we employ daily repeated quasi-natural experiments, where investors’ attention is influenced exogenously by price rounding rather than by stocks’ fundamental information. Our findings demonstrate that stocks included in the Winner List attract significant investor attention, which leads to increased stock price manipulation. A two-stage channel analysis reveals that this increased investor attention exacerbates stock price manipulation through noise trading. Moreover, the positive relationship between investor attention and stock price manipulation is more pronounced in stocks with higher firm-specific information asymmetry, fewer rational investors, weaker external monitoring, higher costs of arbitrage, and non-shortability. Additional analyses indicate that this positive relationship intensifies during periods of heightened investor sentiment, greater economic policy uncertainty and increased geopolitical risk. Our study provides original evidence that the saliency of information exacerbates stock price manipulation and destabilizes financial markets.