Robinhood, a free-trading investment management app, said it experienced an outage as U.S. markets opened on Monday, Bloomberg reports.

Why it matters: The outage cut Robinhood users out of Monday morning's stock rebound of more than 2%, the first gain in eight sessions.

The company said in December 2019 that it has around 10 million users, according to CNBC.

What they're saying: Unable to make trades, clients criticized the platform on social media.

“We are experiencing a system-wide outage," the company said in a message to clients, according to CNBC. "We are working to resolve this issue as soon as possible."

Our thought bubble, via Axios' Jennifer Kingson: Many Robinhood customers are new to investing and may never have experienced market losses of the sort they may have suffered in the last several sessions.

Volatility tends to cause spikes in trading activity, making today a particularly bad time for the platform to go down.

As of noon ET, users were still reporting difficulties with the site on social media.

Go deeper: Wall Street rebounds after coronavirus correction