"The rating actions reflect Moody's assumption that there is now a lower likelihood that these banks would receive external support, if required," it said.
It noted that EU rules restricted support and that Germany had set up a bank resolution scheme.
Nevertheless it said the ratings of the state-backed banks, mostly what are known as Landesbanken, still incorporate a high expectation of support as they are ultimately publicly-owned and account for more than one third of lending and deposits.
The actions affected the senior debt and deposit ratings of the banks.
BayernLB and Deutsche Hypo both had their ratings lowered by three notches to "Baa1" from "A1."