CEO Meg Whitman avoided calling it a fraud, but said Tuesday that there were "serious accounting improprieties, disclosure failures and outright misrepresentations at Autonomy Corporation PLC."
HP is taking an $8.8 billion charge in its latest quarter largely to align the accounting value of Autonomy with its real value. It said most of that charge was due to the fictional bookkeeping at Autonomy.
The revelation is another blow for HP, which is struggling to reinvent itself as PC and printer sales shrink.
Among other things, Autonomy makes search engines that help companies find vital information stored across computer networks. Acquiring it was part of an attempt by HP to strengthen its portfolio of high-value products and services for corporations and government agencies.
Whitman said Autonomy's financial illusion started to unravel after founder and CEO Mike Lynch left on May 23. A senior Autonomy executive then volunteered information about the accounting shenanigans, prompting an internal investigation, she said.
The case has been referred to the U.S. Securities and Exchange Commission and the UK's Serious Fraud Office, she said. The company will also try to recoup some of what it paid for Autonomy through lawsuits.
HP shares dropped $1.45, or 10.9 percent, to $11.85 in premarket trading. If the shares stay at that level in regular trading, they will set a 10-year low.
HP's net loss for the fiscal fourth quarter, which ended Oct. 31, amounted to $6.85 billion, or $3.49 per share. That compares with net income of $239 million, 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 didn't blame improper accounting, just results that didn't 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, as polled by FactSet.
HP's revenue was $30.0 billion, down 7 percent from last year. That was below analyst expectations at $30.5 billion.
HP stuck to its previously given earnings forecast for the fiscal year that just started, but it issued a forecast for this quarter that was well below analyst expectations. It expects earnings, excluding items, to be 68 cents to 71 cents per share, while analysts were looking for 85 cents, according to FactSet.