SAN FRANCISCO — Desperate to shore up Hewlett-Packard, former CEO Leo Apotheker rushed the purchase of Autonomy and his successor, Meg Whitman, duped shareholders about the success of the acquisition, plaintiffs in a securities class action over the ill-fated deal contend.

HP was besieged by a wave of shareholder suits after announcing an $8.8 billion writedown of Autonomy due to revelations of accounting improprieties at the British software maker in November. Defense lawyers for HP and several of its executives argued in motions to dismiss filed in July that it would make no sense for HP insiders like Whitman to cover up fraud at Autonomy and then voluntarily disclose it, as plaintiffs alleged. But plaintiffs lawyers countered in a response brief filed Friday evening that the beleaguered executives were trying to save face.