Simon Property Group is preparing a new offer for General Growth Properties, a month after being turned down by its largest rival, according to a person with knowledge of the plan.

Simon’s lawyers said in a 15 March letter to General Growth’s attorneys that it would make its new offer later this week or early next week, according to the person, who asked not to be identified because the correspondence is private. Simon, based in Indianapolis, also indicated that it planned to address antitrust and financing concerns over the deal, the person said.

Simon last month offered to purchase bankrupt General Growth for more than $10bn, a bid the Chicago-based company said was too low.