During market downturns, the correlation between Bitcoin and Ethereum often increases as both are considered relatively safer assets within the cryptocurrency market. Investors tend to flock to these major cryptocurrencies, causing their prices to move in a more synchronized manner. However, the correlation with smaller, more speculative cryptocurrencies may decrease. These smaller coins may be more vulnerable to market sentiment and individual project - specific factors, and during a market decline, their prices may drop more significantly or in a different pattern compared to Bitcoin and Ethereum. In an uptrend, the correlation between different cryptocurrencies may also change as new investment themes emerge, and different sectors of the cryptocurrency market may perform differently.