Standard & Poor's (S&P) has revealed the impact of its new bank rating criteria on the largest Australian banks, with the outcome for the big four matching most analysts' base case scenario: a one notch downgrade to AA- from AA, but with a stable outlook on the new rating. The big loser in the announcement is Macquarie Group, which is downgraded to BBB from A-, although its subsidiary Macquarie Bank retains its A stable rating.