[LeonenTheDK]

I recently listened to a podcast episode which featured a gentleman who teaches mainframe related things at a university in the US and is deeply involved with the Open Mainframe Project. His statistic was 95% of financial transactions touch a mainframe somewhere along the way.

From what I know, considering it's not "just" banks but pretty much any long running financial business (IE insurance companies), I believe it's one of the most used but least talked about technologies out there.

[mrobins]

Can confirm. In a past life I had the pleasure of auditing the COBOL code of a major US insurer. They had a separate program for every line of service (Auto/GL/etc.) that would read every claim record and produce their actuarial tables.

It was pretty fascinating to see how it all came together. Also despite the languages age after analyzing it for a length of time it was clearly elegant for that type of financial processing.

[JohnFen]

Not just financial businesses. For instance, I worked on a product also used by one of the largest package shipping companies. A couple of their key systems consisted of mainframes running COBOL code.

[rbanffy]

If you like to listen to podcasts and are curious about mainframes, get Terminal Talk. It’s a lot of fun and the mainframe ecosystem is a completely alien biosphere totally different from the Unix space we are more used to see.