Traders Frustrated by Online Brokerage Outages as Stocks Surge

Several online trading platforms around the world broke down or were unavailable on Monday as individual investors tried to take advantage of heavy trading after the announcement of positive data from a Covid-19 vaccine candidate.

More than 85% of S&P 500 companies climbed and shares in industries beleaguered by the pandemic — ranging from travel to leisure — shot up on optimism about a vaccine that prevented more than 90% of symptomatic infections in a trial of tens of thousands of volunteers.

The glitches were the latest instance this year of online platforms freezing up just as non-professional traders turned to them ...