Attorneys for a Michigan pension fund alleged in a shareholder lawsuit filed Wednesday that Mattel Inc. has misled investors by delaying the reporting of defects in its toys to federal regulators.

The lawsuit, filed in Delaware’s Court of Chancery, also accuses three current members and one former member of Mattel’s board of directors of engaging in illegal insider trading by dumping more than $33 million in stock before the company’s massive toy recalls this summer.