Shares in computer giant Hewlett-Packard fell by more than 10% on Tuesday, as the company faced an $8.8bn writedown on its acquisition of UK software firm Autonomy, offering a smart return for holders of put option strategies.

In a statement accompanying its earnings release on Tuesday, HP accused Autonomy of "serious accounting improprieties" and "outright misrepresentations" designed to inflate its value ahead of its agreed $11.7bn sale to HP last August. Autonomy's then chief executive Mike Lynch has strenuously denied the charges.