KPMG and Deloitte are being sued by an HP shareholder over their role in HP's purchase of UK software firm Autonomy.
Philip Ricciardi, who has been an HP shareholder since 2007, filed a lawsuit against the two firms in San Jose, California on Tuesday.
The lawsuit accuses the auditors of failing in their duty to see that Autonomy wasn't worth what it claimed and misrepresenting the deal's value.
As well as the auditors, the case is brought against Lynch, current HP chief executive Meg Whitman, former HP chief executive Leo Apotheker and Barclays and Perella Weinberg Partners, who were financial advisers on the deal.
Last week, HP wrote off $8.8bn on its $11bn acquisition of Autonomy, saying around $5bn of this was due to "accounting improprieties".
HP shares fell 12% to a 10 year low and it is expected to face lawsuits by investors seeking to compensate for their losses.