Citigroup Inc

Last Friday, the first wave of bank earnings reports hit Wall Street, when JPMorgan Chase & Co., Citigroup Inc., and scandal-stricken Wells Fargo & Co. released their first-quarter financials.

Now, ask any one random person in a "Man in the Street"-style interview what they'd expect of the "Too Big to Fail" banks' performance, and I'd bet you would get a shrug and hear something like, "I dunno – they probably made a ton of money, right?"

And that random person would be right… by about half. The big banks do make a ton of money, to be sure, but that's not the most important reason to sit up and pay attention.

That's right: Even if you don't own a single share, big bank earnings calls are a can't-miss event.

Listening to the big bank conference calls is like listening in on closed-door conversations with the U.S. financial industry's most powerful players.

These bankers not only control most of the economy's loans and deposits, but they also get a very clear picture each quarter of how individuals and businesses are faring and where they appear to be heading.

The calls are a road map, essentially, or a cheat sheet that can give you some dynamite investing ideas, not to mention precious intelligence on the state of the American economy.