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



The chipmaker Advanced Micro Devices is down 18.2%, or $2.48, at $11.14 a share on Tuesday after the company said it expected second-quarter gross margins to come in at about 33%, down slightly from the first-quarter reading of 34%.

AMD is the No. 1 stock held by millennials on Robinhood, according to the company's data scientist, Sahill Poddar. AMD is also a popular stock among Robinhood's other users, ranking fifth behind Apple, Amazon, Tesla, and Facebook.

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

The stock-trading app recently earned so-called unicorn status with a $1.3 billion valuation driven by its 2 million accounts, according to cofounder Baiju Bhatt.

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

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