“If this had happened yesterday, before the presidential debate, it would have caused upheaval in the markets,” Mr. Kubota said, with investors losing the opportunity to make short-term trades based on the candidates’ performances.
Futures tracking the market were calling for a modest rise Friday, suggesting that investors were not overly concerned. Mr. Rogers, of Rogers Investment Advisors, said one disrupted day would have minimal effect on his firm.
Others felt the impact more. Invast Securities, a Japanese online securities brokerage, was slated to begin trading on Thursday on Japan’s Jasdaq exchange, which is also operated by the Japan Exchange Group.
“This has turned into a day we’ll never forget,” Invast Securities’ spokesman, Yasuharu Kawada, said.
Japan’s markets have been on the mend. Stocks in Tokyo crashed in March because of investors’ fears about the pandemic’s economic effects. Prices have recovered in the months since, with investors flooding into companies, such as pharmaceutical firms, expected to benefit from the global fight against the virus. Shares are down more than 5 percent since the beginning of the year.
The Tokyo Stock Exchange introduced its current market data system in 2010 and upgraded it in November to speed up transactions amid higher trading volume. The system, known as Arrowhead, was developed by Japan’s Fujitsu Limited, which said it was working with the market operator to address the problem.
The Japan Exchange Group said it took full responsibility for the problem.
Japan has faced similar problems over the years, with system glitches occasionally stopping some trading for brief periods. The last systemwide shutdown was in 2005, when a software upgrade malfunctioned, shutting down the market for half a day.