Are markets sentiment driving the price bubbles in the virtual?

This paper investigates the existence of speculative bubbles in four crypto-market components (Bitcoin, Ethereum, CRIX index, DeFi pulse index) while date-stamping them, before using a wavelet coherence approach to look after the co-movement of each of those four digital tokens with three sentiment indices reflecting three different markets (Stock, gold, and crypto markets). Thereafter, we study the sentiment-price return connection and its concordance with periods of existing bubbles. Our results show the existence of multiple bubble regimes in the virtual market and more specifically, a huge bubble occurring during the crypto-market bull phase for Bitcoin, Ethereum, and CRIX. Moreover, we find that the bubbles that occurred during the COVID-19 pandemic concord with periods of high sentiment co-movement with the three markets. Hence, some of those bubble periods are in phases with periods of high co-movement with sentiments toward different markets. In addition, the fear and greed toward the crypto-market seem to be the leading sentiment index that highly influences the crypto-market components and their bubble appearances.