Popular mobile stock-trading app Robinhood has raised a fourth round of funding for $110 million, giving the young company a valuation of $1.3 billion, the company announced Wednesday.

The Palo Alto, California, firm is a member of Inc.'s 2017 30 Under 30, a group of companies run by brilliant young entrepreneurs. Since its launch in 2015, Robinhood has caused waves throughout the financial services market with its commission-free business model. With the latest funding round, which was led by DST Global, the company has now raised a total of $176 million.

Robinhood's mission is to democratize access to financial markets by making it easier for young adults to get started with their investments. Its commission-free approach has enabled it to quickly grow to more than 2 million users, driving more established rivals to lower their own commission fees.

"We're not going away. Free trading is here to stay," said Baiju Bhatt, Robinhood's co-founder and co-CEO. "We're never going to charge you for trading. We're never going to start jacking up the account minimums."

Robinhood said it has handled more than $50 billion in transactions since its launch, and saved its users $500 million in commission fees.

"We've literally taken half a billion dollars out of the financial system and given it back to the American consumer," Bhatt said. "That's something that we're really proud of."

Until recently, Robinhood has been free to use, but last year, the company launched its $10 a month premium Robinhood Gold subscription service, which gives power users the ability to trade in pre- and after-markets. Bhatt said that service been growing by 17 percent on a month-to-month basis, adding that the company's revenue growth is healthy.

By crossing the $1 billion valuation mark, Robinhood is now a member of Silicon Valley's elite unicorn club, and will surely be drawing more attention. Bhatt said he hopes the company will go public in the next three to five years.

"The reason I work hard on Robinhood every single day is because I actually really like building products that consumers use," he said. "Whether we're worth $10 million or a billion dollars, it doesn't matter. The reason I show up every day is the same."

EXPLORE MORE 30 Under 30 2018 COMPANIESRectangle