A computer systems problem is being blamed for paralysing the London Stock Exchange (LSE) for several hours today - the last day of the financial year.
Share trading still had not started by mid-afternoon and traders were left at a loose end while the problem was investigated.
A spokeswoman for the LSE said the problem is with the exchange's price feed - the London Market Information Link.
"We will restart the system once we know the outcome, and we are doing everything we can to investigate the problem," she said.
She could not say what time the exchange would reopen, but said that it is considering an extension to market hours to "facilitate the completion of business".
Richard Holway of analyst group Richard Holway said: "Here we are on the last day of the financial year when everyone is trying to crystallise their financial gains, one day after the biggest fall on the Nasdaq in an extremely volatile market. Out of all the 365 days of the year for a system to go down to achieve maximum effect, today is the day."
A stockbroker who did not wish to be named said: "We are paralysed. Nothing like this has happened before. I am extremely annoyed."
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