A shareholder lawsuit claims corporate leaders at the Conagra Brands food company acted negligently and unjustly enriched themselves with the $11 billion purchase of a rival manufacturer.

The complaint accuses Conagra of touting the 2018 acquisition of Pinnacle Foods as a “no brainer” without performing sufficient due diligence, causing its stock price to plunge when Pinnacle’s poor performance was eventually revealed.

Shortly before the merger, Conagra’s CEO, Sean Connolly, described Pinnacle as a “juggernaut” and “terrific business” whose brands — including Birds Eye frozen products — will serve as a complementary “bolt-on” to its own product lines.

A few months later, however, after the purchase had closed, Connolly admitted there was “deterioration” in Pinnacle’s performance, with its sales coming in “below expectations” due to “subpar innovation and executional missteps,” the complaint said.

Wall Street analysts criticized Conagra’s leadership for being unaware of “warning flares” and conducting “lax due diligence” of the deal, since the problems described at Pinnacle appeared to be deeper than just a short-term sales decline cause by competitive pressure, the lawsuit said.

In the final weeks of December 2018, Conagra’s price per share dropped nearly 28%, from about $29 to $21, the complaint said. The company’s share price has since recovered to about $28.

Aside from Connolly, Conagra’s CEO, the lawsuit also names the company’s chief financial officer, corporate controller and eight members of its board of directors as defendants.

The lawsuit accuses them of breaching their fiduciary duties by “willfully or recklessly” failing to disclose the problems faced by Pinnacle, violating securities law and unjustly enriching themselves through “lucrative insider sales” or through “bonuses, stock options or similar compensation.”

The complaint seeks damages in an amount to be determined during litigation, as well as corporate reforms at Conagra to prevent “a repeat of the damaging events.”

A representative of Conagra said the company has no comment about the allegations.