Sears Holdings Corp. has hired M-III Partners LLC to prepare a bankruptcy filing that could come as soon as this week, according to people familiar with the situation, as the cash-strapped company that once dominated American retailing faces a debt payment deadline.

Employees at M-III Partners, a boutique advisory firm, have spent the past few weeks working on the potential filing, the people said. In recent days, M-III staff have been at the retailer’s headquarters in Hoffman Estates, Ill., one person said. Sears continues...