When Wells Fargo (WFC 1.42%) reported earnings last week, it gave banking investors several possible trends to look out for as the other banks report, such as shrinking net interest margins and a slowing mortgage pipeline. These will both be key as Citigroup (C 2.24%) reports as well. Motley Fool financial analyst Matt Koppenheffer also tells us in the following video that we should also be watching for Citigroup to reduce its Citi Holdings, and keeping an eye on what new CEO Michael Corbat's next move will be.