We investigate asset returns using the concept of beta herding, which measures cross-sectional variations in betas due to changes in investors’ confidence about their market outlook. Overconfidence causes beta herding (compression of betas towards the market beta), while under-confidence leads to adverse beta herding (dispersion of betas from the market beta). We show that the low-beta anomaly can be explained by a return reversal following adverse beta herding, as high beta stocks underperform low beta stocks exclusively following periods of adverse beta herding. This result is robust to investors’ preferences for lottery-like assets, sentiment, and return reversals, and beta herding leads time variation in betas.