Shares of Howard Hughes rose Monday but were below Ackman’s offering price. It may take more from Pershing Square to seal a deal.

Bill Ackman ’s Pershing Square Capital Management is proposing to merge its newly formed subsidiary with Howard Hughes Holdings Inc., Ackman’s latest attempt to transform Howard Hughes into an empire on par with Berkshire Hathaway.

Howard Hughes (HHH) was up 11.3% in premarket trade after billionaire hedge fund manager, Bill Ackman, through Pershing Square issued a proposal that would increase its holdings in HHH.