RIO DE JANEIRO & SAO PAULO--(BUSINESS WIRE)--Fitch Ratings has today affirmed the Issuer Default Ratings (IDRs), National Ratings, Viability Rating (VR), Support Rating (SR) and Support Rating Floor (SRF) of Banco do Brasil S.A. (BdB). A full list of rating actions is at the end of this press release. KEY RATING DRIVERS IDRS, NATIONAL RATINGS AND SENIOR DEBT BdB's IDRs, National and senior debt ratings are driven by sovereign support and equal to Brazil's sovereign ratings. They reflect the maj