Key Findings
Concentrated Trading Activity
Robinhood users show more concentrated buying behavior than other retail investors, with 35% of net buying concentrated in 10 stocks versus 24% for general retail investors
Negative Returns After Herding
Stocks experiencing intense buying by Robinhood users ("herding events") show average 20-day abnormal returns of -4.7%, with more extreme herding events showing returns up to -19.6%
App Interface Impact
The Robinhood app's simplified interface and "Top Movers" list influences trading behavior, leading users to trade both extreme gainers and losers unlike other retail investors
Trading Concentration Comparison
- Robinhood users concentrate 35% of net buying in top 10 stocks
- General retail investors concentrate 24% of net buying in top 10 stocks
- Shows higher herding tendency among Robinhood users
Returns Following Herding Events
- 20-day abnormal returns average -4.7% for herding events
- Returns become more negative as herding intensity increases
- Most extreme herding events (750% user increase) show -19.6% returns
Impact of Market Cap on Returns
- Small-cap stocks (<$1B) show -3.8% to -4.3% returns after herding
- Large-cap stocks (>$1B) show no significant return pattern
- Effect is stronger during COVID-19 period (after March 2020)
Contribution and Implications
- First study to show how fintech app design influences retail trading behavior
- Demonstrates that simplified interfaces can lead to concentrated trading and losses
- Highlights need for balanced information display in trading applications
- Questions effectiveness of "gamification" in investment platforms
Data Sources
- Trading concentration data from Table III comparing Robinhood and TAQ retail trades
- Returns analysis based on Table VIII showing event-time abnormal returns
- Market cap analysis derived from Table XII showing subsample return patterns