Fitch's rating for Brazil -- where President Dilma Roussef is fighting calls for her impeachment-- now stands at "BB+", down from Fitch's previous "BBB-" rating, it said in a statement.
Brazil's worse-than-expected recession and increased political uncertainty were both weighing on Brazil's ability to honour its debts, it said, adding that its outlook for the country's rating remained negative.
In early September rating agency Standard and Poor's had already given Brazilian debt junk status.