NEW YORK--(BUSINESS WIRE)--Fitch Ratings has today affirmed AllianceBernstein LP's (AB) long-term and short-term Issuer Default Ratings (IDRs) at 'A+' and 'F1', respectively. The Rating Outlook is Stable. Fitch has simultaneously withdrawn the ratings for commercial reasons. KEY RATING DRIVERS IDRS AND SENIOR DEBT AB's ratings reflects its strong investment management franchise, particularly in fixed income, low financial leverage, solid interest coverage, and improving operating performance. T