They want to play “gotcha”. And they are usually libs.
I am not going to do your homework. You do your homework.
But one little hint. CHEAP MONEY BY THE FED!
Why cheap money by the FED? To hold up the FM twins, the banks that went over the edge, etc., but of course the builders also got in on the cheap money and the same banks that went for sub prime loaned money to the building industry because they had to get themselves a better balance sheet position, which they did by selling said loans to the FM twins and foreign banks.
In other words, in trying to get out of the loop, it fed on itself.
Read up on derivatives, why AIG mortgage insurance made it possible for banks to show reserves as being better than they really were and why this broke AIG.
Please do your homework and quit asking questions when the answers are so easy to get in thousands more words and detail than I am able to type.