Robinhood, a zero-fee stock-trading app popular among millennials, confirmed its series D funding round of $363 million.

The round places the company's worth at $5.6 billion.

Robinhood says it will use the money to snag new talent, offer more financial-service options — among them a cryptocurrency-trading platform — and spearhead product growth.

In March, The Wall Street Journal reported that Robinhood, a commission-free stock-trading app, could be valued in excess of $5 billion. The newspaper's unnamed sources said the company was raising an estimated $350 million funding round led by a longtime investor, the investment firm DST Global.

Now, Robinhood is confirming both the size of the series D funding round, at $363 million, and the company's current valuation of $5.6 billion, making the five-year-old startup a formidable contender in the fintech-stock-trading market.

It's remarkable growth for the young company, which, in its first attempt to secure funding, was rejected 75 times.

The round brought in new investors like Kleiner Perkins, Sequoia, Iconiq, and CapitalG, said Vlad Tenev, a Robinhood cofounder. Tenev told Business Insider that Robinhood would use the money to launch new products, scale the product's growth, and snag new talent. Most recently, Robinhood brought on the Greylock investor Josh Elman as its vice president of product.

"We're expanding our product suite so that we can offer many financial services at the lowest possible price," Tenev said.

Robinhood's primary offering is a zero-fee trading app that has taken off among millennials. The company is rolling out a cryptocurrency-trading platform, where users in 10 US states can trade in fiat currencies for digital coins like bitcoin and ether.

Tenev declined to share the number of users trading in cryptocurrencies through Robinhood's app but said there was a "huge demand" for the service.

"We're working as fast as we can," Tenev said.

Like its stock-trading options, Robinhood's cryptocurrency-trading platform is also commission-free. Tenev said Robinhood would buckle down on its cryptocurrency offerings in the coming months.

"Cryptocurrency platforms have exorbitant fees, and they're hard to use," Tenev said. "I think it's fair to say that our goal is to build the best product on the market, where users can have all of their investments in one place."