The U.S. Securities and Exchange Commission on Wednesday approved rule changes to allow the creation of bitcoin exchange-traded funds in the U.S., a long-awaited move that will give regular investors access to the controversial and volatile cryptocurrency.The decision will likely lead to the conversion of the Grayscale Bitcoin Trust, which holds about $29 billion of the cryptocurrency, into an ETF, as well as the launch of competing funds from mainstream issuers such as BlackRock's iShares and F...