These batch jobs are not necessary COBOL. It can be anything from modern Python, Scala, Java to more esoteric choices like Smalltalk, K and bash. I know because

These batch jobs are not necessary COBOL. It can be anything from modern Python, Scala, Java to more esoteric choices like Smalltalk, K and bash. I know because I worked in large investment bank writing Smalltalk for risk management. Banks need to follow regulatory regime. Batch jobs are very convenient, they usually produce flat files that can archived, easy readable by humans and can be consumed in downstream systems regardless of programming languages. My biggest beef with CSV format is multiple specification and poor tooling. Transaction can completed instantly but risk, reporting, regulatory and reconciliation would be performed later as batch job.