Herding Insider Traders: The Case of Opportunistic Insiders

In this study, I used regression analysis to examine the relation between stock return dispersion from the market returns and market portfolio returns as a measure of herding behaviour in opportunistic insider traders from 2014 to 2024 in the USA. Opportunistic insiders place a trade in the same calendar month for at least three consecutive years. I found no evidence of statistically significant and negative relationship between return dispersions and market returns, either absolute or squared. This result implies that there is no herding behaviour. The results are robust to large stock price movements and changes in market volatility. My results are important for regulators and investors. Future research may involve the herding behaviour of insiders who follow trading plans.