Online brokerages including Robinhood Markets and Charles Schwab Corp. were hit again Wednesday by service disruptions as traders were transfixed by wild swings in shares of GameStop Corp. and other heavily shorted stocks.

TD Ameritrade Holding Corp., Morgan Stanley’s E*Trade and Fidelity were also affected, according to Downdetector.com, which tracks user complaints.

Robinhood said it managed to resolve problems with its web app, while Schwab said some clients were struggling with online trading because of a technical issue.

TD Ameritrade said that unprecedented volumes may have curtailed access to its mobile app. “Please consider using our website or other platforms,” the company said in the tweet.

Schwab clients also were experiencing trouble amid “heightened trading across the market,” spokeswoman Mayura Hooper said in an email. “We are working to resolve the issues as soon as possible and will work with all clients to ensure their situations are made right.”

A Fidelity spokeswoman said the company had resolved the issues with its platform. E*Trade declined to comment.

This article was provided by Bloomberg News.