[b20000]

it all just lives in a bunch of csv files on a few people’s PCs and every night a 62 year old man copy pastes it together and checks everything and then uploads it to some old mainframe. he is the only one who knows how to do that job.

[kul_]

I cannot tell if this is a serious comment.

[0xBDB]

It isn't, but it's not that far from being a serious comment.

The old man has an ancient PC choking on dust under his desk that runs a QWS3270 terminal that updates the mainframe directly. If it's a big bank, the bank owns the mainframe. If it's a small bank, a vendor (probably Fiserv) does.

Source: I've consulted for a lot of banks.