Mall operator Simon Property boosted its hostile bid for rival Macerich by 5 percent to $16.8 billion and says that will be its best and final offer. Simon says it is willing to pay $95.50 per share for Macerich, up from its previous offer of $91 per share. Macerich rejected Simon's first bid, saying the deal undervalued the company. The new offer is valued at $23.2 billion, when debt is included. Simon Property Group, an Indianapolis real estate investment trust, went hostile earlier this month after saying that Macerich refused to negotiate a deal that would combine the two largest U.S. mall operators.