Essays On Retail Investor Behavior In Financial Markets

This dissertation examines the trading behavior of retail investors using large datasets and both causal inference and structural estimation methods. The study has two main objectives: to understand the heterogeneity across different investors and to quantify the price impacts of various trading behaviors. Chapter 1 uses data on account-level stock holdings to quantify the importance of different mechanisms contributing to stock booms and busts during the 2015 Chinese stock market bubble. By estimating a structural model of heterogenous investor demand, I find that retail investors account for 78% of the variance in cross-sectional stock returns, but the contribution of different channels varies as the bubble evolves. Chapter 2 studies retail investors' return-chasing behavior leveraging the same data on 18 million individual equity accounts. I find that return chasing predicts both investor returns and stock returns more strongly than various other investor characteristics. Chapter 3 documents the decline in the average profitability of IPOs in the United States between 2010 and 2022. This work provides valuable insights into the drivers of stock price fluctuations and highlights the importance of understanding investor heterogeneity.