The junk stuff was repackaged many times over and sold as separate financial products. That was where the whole rocket scientist quant bs came in as it required

The junk stuff was repackaged many times over and sold as separate financial products. That was where the whole rocket scientist quant bs came in as it required made-up math to make it work. So it was re-rated from crap to AAA. And then AIG started offering insurance against those products and things really started heating up. So it took taking some good bonds and some bad bonds and throwing them into the same CDO to get a good rating.