Shareholders filed a class-action suit in U.S. District Court in California covering shareholders who purchased company stock between Dec. 22 and Feb. 2.
The suit claims Toyota misled investors with "materially false and misleading statements," regarding its business forecast or its operations, The Detroit News reported Monday.
Shareholders frequently file lawsuits when a noticeable error causes stock values to fall. But shareholders will have to "prove knowledge among the corporate management" that the company's statements were misleading, Peter Henning, a Wayne State University law professor, said.
"Unless something else emerges, it seems that Toyota didn't think that it would be the kind of problem it turned out to be," Henning said.
At least one suit demands Toyota install brake override systems in more cars than those already involved in massive recalls that were issued in October and January due to sudden acceleration problems.
Other lawsuits have been filed on behalf of accident victims. The sudden acceleration problem has allegedly caused 51 traffic fatalities.