Simon Property Group Inc.'s offer to buy General Growth Properties Inc. out of bankruptcy for more than $10 billion may start a bidding war for the company, the owner of four out of five of the best-performing U.S. malls.

Simon's proposal would give equity investors about $9 a share. William Ackman's Pershing Square Capital Management LP, General Growth's largest shareholder, said in December the stock is worth $24 to $43. That may spur companies including Brookfield Asset Management Inc., which owns General Growth debt, to place a higher bid, said Jim Sullivan, an analyst with real estate research firm Green Street Advisors.

“;What this bid represents is the start of the game,”; said Sullivan, based in Newport Beach, Calif. “;It pretty much comes down to Brookfield vs. Simon, but I wouldn't rule out other guys trying to get in the game somehow.”;

General Growth, the owner of Ala Moana Center and Ward Centers, filed the biggest real estate bankruptcy in U.S. history in April after amassing $27 billion in debt during an acquisition spree. The Chicago-based company said Tuesday that Simon's offer wasn't sufficient based on discussions with “;other interested parties.”;

Simon Chief Executive Officer David Simon, who said at the time of General Growth's bankruptcy filing that he had tried to buy some of the company's properties, said Tuesday his takeover offer is the best option for creditors and shareholders. The bid would repay unsecured creditors in full for about $7 billion.

“;We are confident it is the best option for all General Growth constituencies and far superior to any other third-party proposal or stand-alone plan that could be completed,”; Simon said in a statement yesterday.

Simon's offer gives Brookfield, other possible bidders and General Growth itself the opportunity to “;step up and let the world know what they want to do,”; said Sullivan.

“;This is a good first bid,”; he said. “;It's not a knock- out.”;