Sears turned in another bleak quarterly earnings report on Thursday, and Lampert complained about the billions of dollars that Sears owes its former employees through pension plans.

Lampert said Sears has paid almost $2 billion into pension plans in the past five years, and $4.5 billion since Sears and Kmart merged in 2005 to form Sears Holdings (SHLD). The company pays retirees about $300 million a year, filings show.

If Sears could have put that money into operations, "we would have been in a better position to compete with other large retail companies, many of which don't have large pension plans," Lampert wrote in a blog post.