Roku on Friday disclosed that 576,000 accounts were accessed by malicious actors.

The California technology company said that it discovered the problem after monitoring unusual account activity on its platform earlier this year that affected roughly 15,000 user accounts.

Roku said that the malicious actors stole the login credentials through a different source and applied a practice called “credential stuffing,” applying stolen usernames and passwords across multiple platforms to take advantage of people who use the same credentials across multiple services.

In fewer than 400 of the cases, Roku said the malicious actors made unauthorized purchases of streaming subscriptions and Roku hardware products, but did not gain access to full credit card information.

“We concluded at the time that no data security compromise occurred within our systems, and that Roku was not the source of the account credentials used in these attacks,” Roku said in a statement.

Wall Street falls sharply to close out its worst week since October

U.S. stocks fell sharply following a mixed start to earnings reporting season. The S&P 500 sank 1.5% Friday.

The Dow dropped 1.2%, and the Nasdaq composite fell 1.6% from its record. Worries about tensions in the Middle East rattled financial markets, and Treasury yields fell as investors looked for safer places for their money.

JPMorgan Chase was among the stock market’s heaviest weights after giving a forecast for a key source of income that was below analysts’ estimates. The pressure is always on companies to produce fatter profits. But it’s particularly acute now given expectations that interest rates may stay high for a while.