Less than a week after agreeing to sell itself to H. J. Heinz in a blockbuster deal, the Kraft Foods Group has found itself the target of a government lawsuit over wheat prices.

The Commodity Futures Trading Commission on Wednesday sued Kraft and its former corporate parent, Mondelez, over what the regulator said in a statement were illicit trades of both wheat futures and other violations of commodity trading rules.

In its complaint, filed in federal court in the Northern District of Illinois, the C.F.T.C. homed in on trades involving wheat futures in the fall of 2011. As the cash price of wheat rose, Kraft Foods, the former parent of both companies, bought about $90 million worth of futures.

The intent was to cause a price drop in the cash wheat market, as sellers were led to believe that Kraft’s trade meant that it would require less of a type of wheat, the commission contended. Yet Kraft never intended to take possession of the wheat tied to the futures contracts, which amounted to a six-month supply for its main mill.