Major steps to prevent a repeat of last month's total crash of the Stock Exchange computers and boost confidence in its IT systems have been taken, MPs were told.
Stock Exchange chairman Don Cruickshank apologised to the House of Commons Treasury Committee for the 5 April breakdown, which cost a full day's trading.
He said that following an Ernst & Young investigation, action to tighten up on systems management and data quality controls were now in place.
Cruickshank said the failure was caused by data corruption and software faults rendering the availability of back-up hardware systems academic.
He revealed action to reduce the possibility of any repetition, a review of contingency arrangements and measures to improve communications with customers and the market.
The Ernst & Young probe discovered that a software problem had affected data processing from the previous evening so it was still running when the next day's business was due to start.