This paper compares the degree of cryptocurrency market efficiency during the pre- and post COVID-19 pandemic with the bubble and non-bubble periods of cryptocurrency markets. Furthermore, it examines and clusters eighteen cryptocurrencies by exploring their market efficiency similarity. Comparing the cryptocurrency bubble periods with the COVID-19 pandemic, the results indicate that this pandemic has the highest impact on cryptocurrency market efficiency. Interestingly, using the dynamic time warping clustering approach, we found evidence on the presence of three clusters that essentially represent mining coins, non-mining coins and token categorizations.

本文将 COVID-19 大流行前后的加密货币市场效率与加密货币市场的泡沫和非泡沫时期进行了比较。此外，它通过探索它们的市场效率相似性来检查和聚类 18 种加密货币。将加密货币泡沫时期与 COVID-19 大流行进行比较，结果表明这种大流行对加密货币市场效率的影响最大。有趣的是，使用动态时间扭曲聚类方法，我们发现了三个集群存在的证据，这三个集群本质上代表了挖矿代币、非挖矿代币和代币分类。