(Photo: Christopher Dilts/Bloomberg)

In the latest round of what has become increasingly commonplace among online trading platforms, Charles Schwab reported that an unspecified “technical issue” prevented at least some clients from being able to log into its online trading platform Monday morning, while Downdetector said outages were also experienced by E-Trade, Fidelity, Merrill Lynch, Robinhood, TD Ameritrade and Vanguard.

“Due to a technical issue, clients may have difficulty logging in,” Charles Schwab tweeted at 10:05 a.m. ET Monday morning. That was about half an hour after Downdetector reported the Schwab outage.

“We’re working to resolve this issue as quickly as possible,” Schwab said, adding: “Hold times may be longer than usual. Thank you for your patience.”

Several people claiming to be clients tweeted in response that they were having problems with Schwab’s app, website and also its phone line when calling to report the issue.

“Some Schwab applications experienced technical issues early this morning which have now been resolved,” Schwab spokesman Peter Greenley told ThinkAdvisor by email just after noon ET Monday. “We are now working to address client questions as quickly as possible. We apologize for any inconvenience this may be causing our clients.”

Fidelity, Merrill Lynch, Robinhood and TD Ameritrade indicated that any issues were caused by excessive trading volumes Monday morning. Indeed, the Dow soared more than 1,000 points Monday morning — more than 4% — after Pfizer announced promising news about a COVID-19 vaccine.

“Customers are able to access our online systems,” a Fidelity spokeswoman told ThinkAdvisor. “Some may have experienced slower processing speeds for a short period at market open due to extremely high volumes, but trades were processed,” she said.

“Like all financial firms this morning, we have been experiencing higher than normal trading volume,” according to Merrill Lynch parent Bank of America. “We currently are not experiencing any issues,” the firm said.

A Robinhood spokesperson told ThinkAdvisor by email: “This morning, despite historic traffic, Robinhood systems remained operational. Our engineering teams have worked diligently to harden our infrastructure, improve reliability, and increase capacity. We’re continuing to invest more than ever in making sure that our systems scale and support our customers on busy trading days.”

Similarly, a TD Ameritrade spokeswoman told ThinkAdvisor: “Earlier today, due to unprecedented volumes of activity, we encountered login issues across multiple TD Ameritrade platforms that impacted some clients’ ability to log in. The issue has been resolved and clients are able to access all TD Ameritrade platforms as usual. We apologize for the inconvenience and take the performance and reliability of our trading platforms very seriously.”

“We understand that some Vanguard clients may have experienced difficulty accessing their accounts on our systems,” Vanguard spokeswoman Dana Grosser told ThinkAdvisor at 11:30 a.m. ET. “The issue has been resolved and we encourage clients to clear their internet cache and cookies, and recycle their web browser, before logging back on,” she said, adding: “We apologize for the inconvenience and thank clients for their patience.”

E-Trade didn’t immediately respond to a request for comment.

On Aug. 31, a multi-system market outage affected many of the largest brokerage firm platforms, with clients taking to Twitter to voice their frustration. Only a few days earlier, TD’s Thinkorswim platform experienced technical issues for several days. That followed multiple outages on the websites of TD Ameritrade and other financial firms earlier this year that led several investors to take to Twitter to complain about trades they were unable to make and money they lost as a result.