The top executives of eight major cryptocurrency firms, including Coinbase Global Inc, will testify before the U.S. House Financial Services Committee on Dec. 8, the panel announced on Wednesday. The hearing marks the first time major players in the rapidly growing crypto markets will testify before lawmakers, as policymakers grapple with the implications of the new financial product and how to best regulate it. Some progressives have become increasingly skeptical of cryptocurrency and the risks they may pose, with Senator Elizabeth Warren, among others, calling for a regulatory crackdown on the volatile sector.