Technology company Hewlett-Packard has written off almost $9 billion (€6.87bn) related to its acquisition of a British software company a year ago.
In a statement alongside its latest financial results HP, which employs around 4,500 people in Ireland, said that there had been "serious accounting improprieties, disclosure failures and outright misrepresentations" at Autonomy.
HP CEO Meg Whitman said executives at Autonomy Corporation PLC "willfully" boosted the company's figures through various accounting tricks, which HP bought in October 2011.
The result, says HP, is that it massively overpaid when it bought the company.
The $11 billion HP paid for Autonomy was almost 80% higher than its value on the London Stock Exchange prior to the takeover.
Autonomy's co-founder - Irishman Mike Lynch - released a statement this afternoon saying he was "shocked to see" the allegations by HP "flatly rejects the allegations", which, he said, are "false".
HP says it has passed information to both the serious fraud office in Britain and to regulators in the US.
The revelation is another blow for HP, which is struggling to reinvent itself as PC and printer sales shrink.
Its shares hit a 10-year low in morning trading in the US.
Autonomy makes search engines that help companies find vital information stored across computer networks.
Acquiring the company was part of an attempt by HP to strengthen its portfolio of high-value products and services for corporations and government agencies.
The computer manufacturer is struggling to reinvent itself as PC sales shrink.
HP's net loss for the fiscal fourth quarter, which ended October 31, amounted to $6.85 billion, or $3.49 per share. That compares with net income of $239m, or 12 cents per share, in the same period last year.
It was the second mammoth loss in a row for HP. In the third fiscal quarter, it lost a record $8.86 billion, or $4.49 per share.
That was due to a charge for another acquisition - that of Electronic Data Systems, a technology consulting service that it bought for $13 billion in 2009.
In that case, HP did not blame improper accounting, just results that did not live up to expectations.
Excluding the charges in the latest quarter, HP earned $1.16 per share in the latest quarter, just above the average analyst forecast of $1.14 per share.
HP's revenue was $30 billion, down 7% from last year. That was below analyst expectations at $30.5 billion.
