While not illustrative of stock market concepts, some discussion of the root assets underlying the drama to follow is needed. With real estate values on an uninterrupted rise from 2002 on, there was great incentive for consumers to buy a house under any circumstances possible and benefit from the rise. Subprime adjustable rate mortgages were pitched as the ideal way for consumers with questionable credit history to do so. The most common were either 2/28 or 3/27 ARMs, with either a two or three year (respectively) flat rate period, after which the rate would float based on some index and some margin specific to the mortgage for the remainder. The intent was that customers with iffy credit would use the flat rate period to repair their credit by making the low payments, and then refinance the home with a prime mortgage using the increase in equity due to the rising market before the rate adjusted and the payments skyrocketed [7]. The housing crisis came about because the bubble burst and that equity was not available. Equity, of course is the balance of the market valuation of the asset with its liabilities. If market valuation drops and the liability (the mortgage) is the same, it's possible to end up with negative equity. This leads to late or defaulted payments, and eventually foreclosure. This left many subprime consumers in an ugly situation by 2007, when the crisis began in earnest as the market froze. As the crisis continued, even prime mortgage holders had problems as their homes lost equity as prices fell.