Millennial investors are getting smoked on a tech stock that's crashing

The most popular stock with millennial investors on Robinhood, a no-fee stock trading app, is tanking.

Chip maker Advanced Micro Devices is down 18.2%, or $2.48, at $11.14 a share, after the company announced it expects second quarter gross margins to come in at about 33%, down slightly from the first quarter reading of 34%.

AMD is the number one stock held by millennials on Robinhood, according to company data scientist Dr. Sahill Poddar. AMD is also a popular stock for Robinhood's non-millennial users, ranking fifth behind Apple, Amazon, Tesla and Facebook.

That means that Tuesday's downturn for AMD could lighten the wallets of a large number of Robinhood's users.

The stock trading app recently earned "unicorn" status after a $1.3 billion valuation, driven by its two million accounts, according to cofounder Baiju Bhatt.

Robinhood became a favorite among younger people looking to invest without paying transaction fees after it launched in December 2014. The app's sleek and simple aesthetic lured in many first-time investors that made up the app's first big wave of users.