Collectively, about 45% of us use one of these banks, they are the Big 4 US Banks: JP Morgan Chase, Wells Fargo, Citigroup and the Bank of America.

And its no accident that these 4 banks lead off the “official” beginning of earnings season each quarter. They are that important to our financial system. Collectively they have 9 Trillion in Bank Assets, not counting their custodial and trading functions. Both of which would increase those numbers geometrically. The Federal Reserve, the nation's central banker, uses these four institutions both to measure the health of the overall banking system, and to implement various fed policies.

So, as investors it is important that we always keep an eye on these 4, even if they don't happen to be in our portfolio currently.