Herding Unmasked: Insights into Cryptocurrencies, Stocks and US ETFs

Abstract: Herding behavior has become a familiar phenomenon to investors, carrying the potential danger of both undervaluing and overvaluing assets, while also threatening market stability. This study contributes to the literature on herding behavior by using a more recent dataset to cover the most impactful events of recent years. To our knowledge, this is the first study examining herding behavior across three different types of investment vehicle. Furthermore, this is also the first study observing herding at a community (subset) level. Specifically, we first explore this phenomenon in each separate type of investment vehicle, namely stocks, US ETFs and cryptocurrencies, using the widely recognized Cross Sectional Absolute Deviation (CSAD) model. We find similar herding patterns between stocks and US ETFs, while these traditional assets reveal a distinction from cryptocurrencies. Subsequently, the same experiment is implemented on a combination of all three investment vehicle types. For a deeper investigation, we adopt graph-based techniques such as Minimum Spanning Tree (MST) and Louvain community detection to partition the given combination into smaller subsets whose assets are most similar to each other, then seek to detect the herding behavior on each subset. We find that herding behavior exists at all times across all types of investment vehicle at a subset level, although the herding might not manifest at the superset level. Additionally, this herding behavior tends to stem from specific events that solely impact that subset of assets. Given these findings, investors can construct an appropriate investment strategy composed of their choice of investment vehicles they are interested in.