If you're trading REITs, brokers take their cut. But like its namesake implies, new app Robinhood wants to democratize stock trading by eliminating the $7-per-trade fee. Launched in December 2014, Robinhood has grown in popularity with Millennials, facilitating over $1B in trades to date.

The app—backed by investors like Snoop Dogg, Jared Leto and Linkin Park—won an Apple Design Award for its simple and stylish design (like how it allows you to log in with your fingerprints) to help make the trading of just about any stock cheap and more mobile. 

To start trading on the app, a user links a bank account to the app to do either a one-time transfer or periodic deposits. The interface is simple and stocks are also displayed with relevant news.

Apps like Robinhood signal a shift in investment trends, particularly among Millennials, geared towards a more tech-savvy audience. And they're big business, too. Last year, online stock brokers raked in billions in broker fees. E*Trade and Scottrade alone posted close to $3B in revenue.

There are currently 198 REITs trading on the New York Stock Exchange, with NYSE-listed REITs totaling $893B in market cap (as of the end of 2014). As of last month, daily trading volume for REITs reached $6.4B.