Sears has "substantial doubt" about its future

NEWARK - Sears, once the monolith of American retail, says that there is "substantial doubt" that it will be able to keep its doors open.Company shares, which hit an all-time low last month, tumbled more than 5 percent before the opening bell Wednesday.Chairman and CEO Edward Lampert's hedge fund has forwarded millions in funding to keep Sears afloat but with sales fading, it is burning through cash.According to its most recent regulatory filing late Tuesday, Sears Holdings Corp. lost more than