Banks (and not only) employ multitude of technologies, all over the place. Personally I encountered mentions of core bank software (as in, the actual account h

Banks (and not only) employ multitude of technologies, all over the place. Personally I encountered mentions of core bank software (as in, the actual account holding code) being available from one vendor in z/OS and OpenVMS versions, some places I know of use DB2 on z/OS for various data, a certain big international powerhouse of a bank has probably everything from IBM z/OS to several cloud offerings. There are also banks that run "pretty modern"... and frankly speaking, that one case I know was the most shitty code - and it still had COBOL, except now with added Oracle in the mix on top of horrible mess of RHEL.