House lawmakers are diving into the Reddit-driven stock rally that upset Wall Street last month.
Small investors on the platform led the frenzy that sent shares in retailers like GameStop soaring.
This caused wealthy corporate hedge funds to lose millions for betting on those companies to fail.
The day trading app Robinhood then faced criticism for temporarily suspending investments in certain companies.
Now lawmakers and regulators are questioning those affected to see if there may be problems with the structure of the markets.