Robinhood

Without a second's hesitation, Vladimir Tenev will tell you the first time he invested in the stock market. He was just 12 but bullish on Palm, the maker of the PalmPilot, a hunch that earned him $1,000. That enthusiasm for mobile tech and the stock market led him to Robinhood, Tenev's startup, co-founded with Baiju Bhatt in 2013. Robinhood is a commission-free brokerage that lets you trade from a smartphone app. "If you're someone who's in your late teens or early 20s and you want to invest a hundred bucks to try it out for the first time, it [used to be] cost prohibitive," Tenev says. He's lured in enough young users to force older rivals like E-Trade and Charles Schwab to cut fees--the same way those firms forced Wall Street wirehouse firms such as Merrill Lynch to reprice trades. The company is focused on making money by providing premium features to its heavy-duty users through a $10 per month subscription service called Robinhood Gold. -Salvador Rodriguez