Andersen Consulting this week confirmed it had been questioned by rival Ernst & Young in its probe into the London Stock Exchange technical breakdown.
The consulting giant was responsible for maintaining most of the system which crashed on 5 April, the last day of the tax year, as investors were attempting to crystallise capital gains and losses.
Ernst & Young was hired by the Financial Services Authority to put together an independent report into the cause of the problem and put forward steps to prevent future problems.
An AC official, confirmed: ‘We co-operated fully with the Ernst & Young team.’
Meanwhile, FSA officials welcomed moves by the LSE to address the issues surrounding the technical breakdown.
Gay Wisbey, FSA director of markets and exchanges, said the LSE had sets out the steps it has already taken and will continue to take in a range of areas to ensure that confidence in its systems is reinforced.
The LSE fully accepted E&Y’s conclusions and recommendations which found that a combination of circumstances affected the processing of data that occurs at the end of each trading day.
Don Cruickshank, chairman-designate of the stock exchange, said: ‘The investigation has identified the series of events that led to the late opening of the market. As a result, additional systems control and managerial measures have been implemented in order to ensure that such a problem should not occur again.’