We find that Robinhood ownership changes are unrelated with future returns, suggesting that zero-commission investors behave as noise traders. We exploit Robinhood platform outages to identify the causal effects of commission-free traders on financial markets. Exogenous negative shocks to...

Retail investors dominate option trading in recent years. Individuals are net purchasers of options, particularly call, short-dated, and out-of-the-money options, although they tend to write long-dated puts. Retail brokerage outages are associated with reduced implied volatility overall, and the...