This is personal productivity computing, not enterprise computing.
In a banking environment, enterprise computing is used to keep track of how much money is in each of millions of accounts, and how much is owed on millions of loans, and process credits and debits into these. You will not find any Apples, or any PCs, involved in this.
Actually, you will. The Aozora Bank, Ltd., of Japan, is 100% run on 2,300 Macs. In addition, at least one Creditcard processing company that I know of runs on xServe Macs running OSX... which, as you may know, is certified UNIX™... which many bank run on their main frames. Here is a photo of the creditcard company's server room of xServe Macs from 2008's Macworld keynote where it was discussed. That's Apple's VP of hardware standing in front of the screen:
Everyone aside from my husband in our family has iphones...he cannot because he consults for an insurance company, and apparently they’re not FINRA certified. He’s stuck with his blackberry...
iPads effectively serve as dumb terminals, while the back-end servers still do the majority of the work. As long as data is transmitted from the iPad to the server, via SSL, there shouldn’t be too much concern about security.