When Bitcoin first began generating headlines, there were some who thought the cryptocurrency was a fraud and others who thought it was the next big thing. Greg King, CEO of Rex Shares LLC, was one of the latter. Like the Winklevoss twins, he set out to create an exchange-traded fund (ETF) that would allow people to invest in Bitcoin in a new way. But many years later, the U.S. securities watchdog hasn't approved such plans. On this edition of the Odd Lots podcast, we use the Bitcoin example and King's experience to explain the inner workings of ETFs.