General Growth Properties Inc., which owns six shopping centers in the Chicago area, including Oakbrook Center in Oak Brook, filed for Chapter 11 bankruptcy protection this morning.

The company, which is the nation’s second largest mall operator, maintains that the properties it owns are sound and will continue to operate as normal during the bankruptcy process. Oakbrook Center has been highlighted by GGP as one of its 22 premier properties out of the more than 200 properties it owns, offering higher-end retailers than other malls it owns.

Bankruptcy protection, anticipated since the fall for GGP, came due to the company’s inability to persuade a majority of its debt holders to give the company more time to refinance billions of dollars in debt it rang up in the last few years.

Wilmington Trust Corp., a financial holding company, has $2.5 billion in unsecured claims from GGP.

“Our core business remains sound and is performing well with stable cash flows,” Adam Metz, GGP’s chief executive officer, said in a statement released today. “We believe that Chapter 11 is the best process for restructuring maturing mortgage loans, reducing the company’s corporate debt, and establishing a sustainable, long-term capital structure for the company.

“While we have worked tirelessly in the past several months to address our maturing debts, the collapse of the credit markets has made it impossible for us to refinance maturing debt outside of Chapter 11."

The release went on to state “all day-to-day operations and business of all of the company’s shopping centers and other properties will continue as usual.”

According to GGP, Oakbrook Center is the largest open-air premier shopping center in the country. It contains six major department stores and more than 160 upscale shops and restaurants.