According to the Wall Street Journal, that filing represents “one of the largest real-estate failures in U.S. history, capping a precarious, months-long effort to juggle the crushing $27 billion debt load it shouldered in past acquisition sprees.”

General Growth is just one of many large property owners that loaded up on debt to finance acquisitions in the past few years, the article continues. They “now face mountains of that debt coming due.”

Why the Galleria, the Burbank Town Center, and more than 50 other properties are outside the filing isn’t clear. A restructuring statement on General Growth’s website says: “Certain subsidiaries, including GGP’s third party management business conducted by General Growth Management, Inc. and GGP’s joint ventures have not filed for protection.”

All malls will remain open for business, and the Glendale Galleria’s hours and operations have not been affected.

In his Traffic Court blog, David Bodamer transcribed General Growth’s media conference call this morning, during which Chief Operating Officer Tim Nolan said in response to a question on selling assets, “Our top 25 properties–some of the best in the country–could we sell 1 of those or 2 of those? Certainly that’s possible. But we think … relative to business plan we’re putting forward that’s not going to be integral part of the restructuring…. We believe we can maintain those.”

Nolan also said, “At the end of the day, our retailers want to be in shopping centers where they can get sales. We have some of the highest production shopping centers in the United States. … We take comfort from the fact that they are prioritizing our malls.”