Robinhood, the free online trading app, announced a new round of funding on Thursday.

The company, which allows its “several hundred thousand” active customers to buy and sell stocks for free, took in $50 million in a Series B round, led by New Enterprise Associates. In 2014, Robinhood received $13 million in a Series A round from Andreessen Horowitz, Google Ventures, and the movie star Jared Leto, among others.

Robinhood said it will use the money to double its employee headcount to 30 in its Palo Alto headquarters, as well as to expand its offering beyond the iPhone and Apple Watch to Android devices, and to explore some international markets, including Australia.

Although the app is available to anyone, the company has a stated goal of focusing particularly on the millennial market of 90 million consumers in the U.S. alone. Founded in 2013 by Vlad Tenev and Baiju Bhatt, Stanford University graduates, the company emerged from beta in December.

Prior to Robinhood, in 2010 the duo founded Chronos Research, which made high-frequency trading software for Wall Street bankers and hedge fund managers.

Nonprofessional traders in the U.S. retail brokerage industry have accounts worth roughly $2 trillion of assets, according to research firm Aite Group. The companies from which Robinhood hopes to steal business include the now old-guard online trading companies such as Charles Schwab, TD Ameritrade, E-Trade, and Scottrade, which generally charge between $7 and $10 per trade.