Using comprehensive account-level data, we separate Chinese retail investors into 5 groups and document strong heterogeneity in trading dynamics and performances. Retail investors with smaller account sizes cannot predict future returns correctly, display daily momentum patterns, fail to process public news, and show overconfidence and gambling preferences, while retail investors with larger account balances predict future returns correctly, display contrarian patterns, and incorporate public news in trading. Using performance measures established in previous literature, we find that smaller retail investors suffer from poor stock selection abilities and trading costs, while large retail investors’ stock selection abilities are offset by trading costs.

We investigate the determinants and effects of firm-initiated trading suspension during the Chinese stock market crash in July 2015. Our findings reveal that firms implemented suspensions to prevent investors’ panic selling, mitigate negative economic feedback, and safeguard specific shareholders’ interests. Once trading resumes, suspended stocks quickly align with the returns of comparable stocks, indicating that investors do not appear to penalize these firms in terms of valuation. Regarding post-resumption trading profits, small individual investors and institutions experience losses, whereas large individual investors and state agencies realize gains.