When you think about it, you're kind of intimate with your bank. Your paycheck and every penny you spend go through the bank. Unless you use cash, everything is in a handy electronic format ripe for data mining.
Banks are taking advantage of that information. The practice is not new, but techniques are evolving. They're increasing efforts to predict who you are and how your finances look.
By knowing about your job loss before you start defaulting on loans (which will muck up your credit report), your bank can get a jump on other lenders. They may limit their risk by cutting credit lines and denying loan requests. They can also use the information to market products and services you're more likely to accept.
Be mindful of what goes on in your bank account and who you bank with. Think about how transactions look, and how things will look if there's a dramatic change. For the most part, there's little to worry about. However, you should know what banks are looking at and evaluate the situation for yourself.
Further reading: