First of all, a bank would not buy a cds for a specific consumer loan. It might buy it for a security that was backed by many thousands of consumer loans, like a mortgage backed security or a credit card receivable backed security.
Here's a basic explanation of a cds from another thread:
A credit default swap is an insurance policy that a bondholder buys. Paraphrasing the colorful names used in the Wiki article, let's say that Penion Fund wants to buy bonds from Risky Corp. It buys $10 million in Risky Corp's bonds which are 7% bonds for 5 years.
Risky Corp pays 7% interest or $700,000 each year. If Pension Fund gets scared that Risky Corp will default, Pension Fund can go to AIG and ask to buy a credit default swap.
Let's say the credit default swap costs 300 basis points (that's a fancy way of saying 3%). So Pension Fund pays AID $300,000 per year out of the $700,000 per year it gets from Risky Corp.
That may sound like a lot but it means (or was supposed to mean) that there was no chance that Penion Fund could lose money. If Risky Corp sends out a letter saying, we've run out of money we're not paying interest and may not be able to pay you your $10 million in year five, under the credit default swap, Pension Fund can go to AIG and say, here's Risky Corp's bond, we want our $10 million back and AIG has to give it to them -- even if Risky Corp's bonds are now selling for $2 million on the open market because of the default.
The worst thing about credit default swaps is that the repugs put a clause in the bankruptcy code that says that credit default swaps are basically exempt from waiting in line during bankruptcy if the issuer (AIG) of the credit default swap goes into bankruptcy.
That means that while AIG's bondholders, suppliers, employees, contractors -- everyone who was owed money -- would have had to wait in line if AIG had been allowed to go bankrupt, while the bankruptcy court tried to figure out how to pay off AIG's debts, holders of credit default swaps, like Pension Fund could just go and demand payment and get it.
Credit default swaps were purchased on trillions of dollars worth of mortgage backed securities, which means that the default of mbs means that certain issuers, like Lehman, are on the lines for billions and billions -- supposedly to be paid before bankruptcy even starts.
3) If, in my hypothetical example, AIG sells BofA a Credit Default Swap, is\was AIG required to maintain any capital reserves against the possibility that the loan would default?
No. Thank Phil Gramm for that. They were considered commodities (like derivatives) but were even exempt from commodity regulation. They were exempt from insurance regulation as well, so there were inadequate reserves.
4) BofA sought insurance against a default, AIG (and its like) sought revenue by insuring against a default. Both parties probably assumed housing prices would continue to rise, hence very little risk. Was the risk all along that the rate of increase in housing prices (the "housing bubble") could not keep indefinitely outpacing increase in median wages?
Yes.