Brian Armstrong

Armstrong is building Coinbase, the biggest U.S. Bitcoin exchange, into what his team hopes will become “the Google of crypto”—as relevant to the next wave of the web as Google was to the last. While it has a way to go, it’s on the right track: During this winter’s investment mania, Coinbase catapulted into the mainstream, eclipsing Charles Schwab in total accounts. Now the company is investing in upstarts and making acquisitions—including one that secured it a path to several tantalizing financial licenses. (Also No. 20 on the main Fortune 40 Under 40 list.)