What happened

Shares of Robinhood Markets (HOOD 0.74%) fell 10.3% on Thursday after the online brokerage released its second-quarter financial results and alerted shareholders to a slowdown in trading activity.  

So what

Robinhood's revenue soared 131% year over year to $565 million. The gains were driven by a surge in cryptocurrency-related transaction revenue to $233 million, up from only $5 million in the year-ago quarter.

Traders have flocked to Robinhood's platform over the past year. Monthly active users jumped 109% to 21.3 million. Its assets under custody, in turn, increased 205% to $102 billion.

"We're encouraged by the number of people who are accessing the financial system for the first time through Robinhood," CEO Vlad Tenev said in a press release. "We're happy to expand access through products like commission-free crypto trading, which saw strong growth this quarter."

To better serve its rapidly expanding customer base, Robinhood ramped up its investments in technology and customer support. This spending weighed on profits, but its adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) still managed to increase by 43% to $63 million.

A person is pointing to a stock chart that rises sharply and then falls.

Investors sold off shares of Robinhood on fears of slowing growth. Image source: Getty Images.

Now what 

Unfortunately, management warned that Robinhood's results in the current quarter are unlikely to be as strong. The brokerage's trading volumes and transaction revenue are heavily influenced by market volatility and investor trading behavior. These factors -- including the meme-stock frenzy and the soaring popularity of cryptocurrencies like Dogecoin (DOGE 4.03%) -- helped to fuel Robinhood's growth earlier this year. But with these trends now abating, the company told investors to expect "lower revenues and considerably fewer new funded accounts" in the third quarter.