Investors ran into trading difficulties Monday as several leading brokerage firms experienced technical issues that limited user access.

The issues arose as the S&P 500 surged in early trading on positive news from Pfizer about its COVID-19 vaccine.

The Charles Schwab Corp. said some of its investor applications had “technical issues" early in the morning, which resulted in some clients being unable to log into their accounts.

TD Ameritrade, which was recently acquired by Schwab, said that due to unprecedented volumes of activity, there were login issues across multiple platforms that affected some clients’ ability to log in.

Both Schwab and TD Ameritrade said the problems were resolved.

Fidelity Investments said its customers were able to access its online systems but that some may have experienced slower processing speeds for a short period when the market opened due to extremely high volumes, but trades were processed.

Stocks jumped Monday, in the first day of trading since the presidential election was called for Democrat Joe Biden, though the moves were driven largely by the vaccine news. Some Schwab clients complained on Twitter and elsewhere saying the technical issue was costing them greatly as they tried to sell on the market’s jump.

Vanguard also said its clients may have experienced difficulty accessing their accounts on Monday. The company said the issue has been resolved and suggested clients clear their internet cache and cookies, and recycle their web browser, before logging back on.

The S&P 500 rose as high as 3.9% Monday but an afternoon decline in some big technology stocks put a damper on the gains. The index closed the day up 41.06, or 1.2%, to 3,550.50.