Autonomy, founded in Cambridge in 1996, was a member of the FTSE 100 and one of Britain’s most valuable software companies before its sale. Mr Lynch made £500m from the deal, using the funds to set up companies including the British cybersecurity company Darktrace.
HP wrote down almost all of the deal’s value a year later, claiming accounting irregularities from Autonomy’s former management.
Mr Lynch and Mr Chamberlain were charged in 2018 and Mr Lynch had fought extradition to the US for years until leaving the UK last year. Priti Patel, the former Home Secretary, had approved his extradition in 2022.
Mr Lynch had consistently argued that any criminal charges should be brought in the UK, where Autonomy was based. The Serious Fraud Office investigated Autonomy but dropped the inquiry in 2015, leaving the case to US prosecutors.
During the trial, prosecutors had sought to tie Mr Lynch to allegedly fraudulent “round-trip” agreements in which Autonomy paid customers to buy its services and accounting fraud that inflated the company’s revenues.
They painted Mr Lynch as an intimidating boss who ruled over all aspects of the business and had compared Autonomy to the mafia.
Mr Lynch had argued that he was not closely involved in the company’s accounting or sales operations. In a four-day stretch on the witness stand, he said he had found watching the trial “surreal”, saying: “I’ve sat and watched a parade of witnesses that I’ve never met.”
He had said that Autonomy was not “perfect”, saying: “The reality of life is that it is nuanced and it is messy, and sometimes you do your best to get through it, and companies are just like that.”
Mr Lynch’s lawyers succeeded in having one of 16 counts against him, concerning securities fraud, thrown out last week.
Christopher Morvillo and Brian Heberlig, legal counsel for Mr Lynch, said: “We are thrilled with the jury’s verdict, which reflects a resounding rejection of the government’s profound overreach in this case.
“The evidence presented at trial demonstrated conclusively that Mike Lynch is innocent. This verdict closes the book on a relentless 13-year effort to pin HP’s well-documented ineptitude on Dr Lynch.
“Thankfully, the truth has finally prevailed. We thank Dr Lynch for his trust throughout this ordeal and hope that he can now return home to England to resume his life and continue innovating.”
Before the trial, Mr Lynch, who has served as an adviser to two UK prime ministers, had been kept under house arrest, subject to 24-hour surveillance.
Abraham Simmons, a spokesperson for the Office of the United States Attorney, said: “We acknowledge and respect the verdict.”
