New York (CNN Business) Would $6 billion in cash have kept Sears out of bankruptcy?

It sure wouldn't have hurt. Sears' ability to stay in business is in doubt after the company filed for bankruptcy protection this month.

Yet Sears spent $6 billion buying back its own shares since 2005 in a futile effort to help support its stock price. The stock plunged more than 99% in value, from a high of $143.91 in 2007 to less than $1 a share a couple of weeks before its bankruptcy filing. In bankruptcy, the shares are essentially worthless.

"If they had put $6 billion into upgrading stores and website development, they could be in a very different position right now," said William Lazonick, a retired University of Massachusetts economics professor and an expert in share repurchases. "They could be in a much better position to compete in the changing world of retail."

Sears could have used the money to reduce its debt burden and provide the working capital needed to keep the company out of bankruptcy.

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