CHICAGO--(BUSINESS WIRE)--Fitch Ratings has affirmed its 'B' Issuer Default Rating (IDR) on SUPERVALU Inc. (SVU), post the company's announcement that it is exploring the potential separation of its Save-A-Lot business through a spin-off of the business into a stand-alone, publicly traded company. The Rating Outlook is Stable. A complete list of ratings is provided at the end of this release. KEY RATING DRIVERS SVU has reported improved operating results over the past two years as it has cut ex