Hewlett Packard says a company it bought last year was not worth anything like the $US10 billion price.
HP on Tuesday accused Autonomy of misleading it by inflating its value prior to the takeover.
The computer maker has written down the value of the business by $US8.8 billion and asked agencies in Britain and the United States to investigate.
The charge wiped down HP's quarterly profit, pushing it into the red by 6 point 9 billion dollars.
Chief executive Meg Whitman accused the company's former owners of "outright misrepresentations" prior to the sale.
HP completed the takeover of Autonomy for $US12 billion in October last year. Autonomy was founded by Mike Lynch in 1996 and became one of the largest software companies in the UK.
