For us we have giant database like applications that consume data across the entire bank to calculate risk indicators. There are all kinds of risk at a bank so it gets pretty complicated with all the products we have. They either generate views for downstream business partners or directly generate reports. The views are frequently over 1000 columns wide and are at an account level (the data is initially transaction level). We also have some web apps to provide a user interface or off the shelf customizable reporting like tableau or microstrategy.
I'm not at a top 3, only a large regional. But I'm going to guess software packages and services from companies like Wolters Kluwer Financial Services (http://www.wolterskluwerfs.com for those interested).
I'm sure we buy tons of products like that. Some of my coworkers worked on Black Knight's MSP before. The costs over there are even more insane. But in my department (a risk department) everything is custom ETL, custom web apps, and custom or off the shelf reporting.
How much of the costs are from the bloat of things like custom web apps and custom reporting? Are newer online-only banks saving substantial amounts of overhead by getting by with the basics and doing their own API integrations?