Mall owner Simon Property Group Inc. sweetened its offer to buy out its struggling rival General Growth Properties Inc. on Wednesday, trying to best a group of investors bidding for the company.

Two months after its hostile bid valued at $10 billion was rejected, Simon said it will match a dueling offer for the real estate investment company and invest $2.5 billion into its reorganization.

Simon, the nation's largest mall owner, said its offer may also include an additional $1 billion investment from prominent financier John Paulson's Paulson & Co.

Simon, which is based in Indianapolis, said Wednesday's offer amounts to $10 a share. Its earlier offer of $9 per share was rejected.

General Growth operates more than 200 shopping malls in 43 states and is the nation's second-largest shopping mall operator.

It sought shelter from creditors a year ago, resulting in the largest real estate bankruptcy in U.S. history. The company, based in Chicago, remains under Chapter 11 protection.

General Growth is considering a competing offer from Brookfield Asset Management and a group of other investors. That deal would inject some $6.5 billion in cash in exchange for shares of the company.

General Growth shares climbed a penny to $16.16 in morning trading Wednesday while Simon shares rose 19 cents to $88.37.