British tech tycoon Mike Lynch has been cleared of fraud charges he faced in the United States over the $11bn (£8.6bn) sale of his software firm to Hewlett-Packard in 2011.

A jury in San Francisco found him not guilty on all counts, a stunning victory for Mr Lynch, who had been accused of inflating the value of his firm, Autonomy, ahead of its sale.

Mr Lynch, who faced more than 20 years in prison if convicted, had denied the charges, taking the stand to defend himself.

In his testimony, he maintained he had focused on technology, not accounting, distancing himself from other executives, including the company’s former chief financial officer, who was already successfully prosecuted for fraud.

Mr Lynch co-founded Autonomy in 1996 and led it as it grew to be one of the UK’s biggest companies.

It was ultimately sold to Hewlett-Packard (HP) in 2011 in a deal that ranked, at the time, as the largest-ever takeover of a British technology business. Mr Lynch made £500m from the sale.

Just a year later, HP wrote down the value of Autonomy by $8.8bn.

Prosecutors argued that Mr Lynch had defrauded investors ahead of the sale, inflating the value of the firm using backdated agreements to mislead about the company’s sales; concealing the firm’s loss-making business reselling hardware; and intimidating or paying off people who raised concerns.

Since trial began in San Francisco in March, they have called dozens of witnesses, including the former head of HP Leo Apotheker, who was fired shortly after the purchase was announced.

But some arguments fell flat. Judge Charles Breyer had already dismissed one count of securities fraud during the trial.

Mr Lynch, a former UK government adviser who sat on the boards of the BBC and the British Library, had vigorously fought attempts to bring him to trial in the US.

First charged in the US in 2018, he was eventually extradited after a UK judge ruled in favour of HP in a similar civil fraud case in 2022. HP is seeking a reported $4bn in that case.

The entrepreneur, who once drew comparisons to the likes of Bill Gates, acknowledged during the trial that the way he ran the company may not have been “perfect”.

As well as Mr Lynch, Autonomy’s former finance executive Stephen Chamberlain was also on trial.

He was also found not guilty.