The company, which has announced several staff reductions in recent months, was working with investment bank Lazard and law firm Sidley Austin to find financial options, the Chicago Tribune reported.
The company filed on the day a $70 million unsecured debt came due. It has been struggling to work its way through a $13 billion debt incurred when real estate businessman Sam Zell bought the company in a leveraged buyout a year ago, the newspaper said.
The company reportedly had $300 million cash on hand, but executives could not find lenders willing to help it restructure its debt. Another $512 million principle payment on the leveraged bailout is due in June, the Los Angeles Times reported.
The company's filing in a Delaware court said it owed $13 billion against company assets of $7.6 billion. Its ownership of the Chicago Cubs was not part of the filing, the report said.
The Cubs were to be sold earlier this year, but the economic downturn stalled that sale, which is expected to take place next year, the Times said.
2014: The Year in Music [PHOTOS]