By now, almost everyone in financial markets is familiar with ETFs (exchange-traded funds), and how they allow investors to move quickly in and out of a basket of stocks with a few clicks. But perhaps people don't realize quite how revolutionary they are, and how much of an impact they've had on the financial system. On this week's episode we talk to Eric Balchunas, an ETFs analyst at Bloomberg Intelligence and Joel Weber, the editor-in-chief of Bloomberg Markets magazine about how extraordinary ETFs are, how far they've come, and how they're about to evolve and get even more gigantic.