Closing auction volume steadily increased over the last decade, and it reached a peak of about 10% of the total trading volume in 2019. We examine the price impact and resiliency of closing auctions, and we compare closing auction liquidity in Nasdaq and the NYSE. The NYSE offers more depth. In both exchanges, it takes about 3–5 days for the temporary component of the price impact to fully dissipate. Trading strategies that exploit this price impact and its reversals are significantly profitable.

We study brokerage platform outages to examine the impact of retail investors on financial markets. We contrast outages at Robinhood, which caters to inexperienced investors, with outages at traditional retail brokers. For stocks with high retail interest, we find that negative shocks to Robinhood investor participation are associated with reduced market order imbalances, increased market liquidity, and lower return volatility, whereas the opposite relations hold following outages at traditional retail brokerages. The findings suggest that herding by inexperienced investors can create inventory risks that harm liquidity in stocks with high retail interest, while other retail trading improves market quality.