Robinhood Markets (NASDAQ: HOOD) shook up the financial services industry by offering "free" unlimited stock trading and a mobile-first approach. While the buzz around Robinhood has faded since its peak during the pandemic, the trading platform still carries significant influence, especially with millennials -- the age of the average account holder is estimated to be just 31. Robinhood also shares a regularly updated list of the 100 most popularly held stocks among users of the platform, making it easy for investors to know what stocks younger investors and Robinhood traders like.