November 24, 2008 – 2:59 am 
So what is the capital cushion underneath our largest financial institutions? I spent today compiling this spreadsheet:
Those are some ugly numbers and I’ll explain why. Citigroup’s leverage ratio of 56 means that the bank has $56 of assets for every $1 of common equity. If the value of those assets falls 2%, then common stockholders are wiped out. Here’s why: Assets = Liabilities + Equity. If you understand this formula, you will understand the credit crisis. So read on…
That formula is known as “the accounting equation.” Fundamentally, it shows how an asset (like a house) or collection of assets (like a company) is financed—either with borrowed money or your own, with debt or with equity.
One side of the equation has to equal the other. If the assets fall in value, and not because cash was used to pay off a liability, then equity has to fall by an equal amount. If assets fall far enough, then equity falls below zero.
http://optionarmageddon.ml-implode.com/2008/11/24/leverage-by-the-numbers/