The Ten Percent Rule, Rules!

"If it is too complicated for most of us to understand in 10 to 15 minutes, then we probably shouldn't be doing it."
Christopher Whalen of Institutional Risk Analytics, quoted in
Nelson D. Schwartz & Julie Creswell, "What Created This Monster?/Yes, the Markets Can Bite Back" p. 1, col. 1 "Sunday Business" Section (New York Times Nat'l Ed., Sunday, March 23, 2008).

Then there are these thoughts in the same newspaper article:

    Credit rating agencies, which banks paid to grade some of the new products, slapped high ratings on many of them, despite having only a loose familiarity with the quality of the assets behind these instruments.
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    Ratings agencies have similarly been under fire ever since the credit crisis began to unfold, and new regulations may force them to distance themselves from the investment banks whose products they were paid to rate.

There is nothing like a hands-on inventory or, if that is not an option, then there is nothing like knowing enough to know that you do not know, everything.

Please Read The Disclaimer.