AIG wasn't a bank but it was insuring a lot of the bank's assets, including securitized mortgages. By taking that risk off the banks' balance sheets, they let t

AIG wasn't a bank but it was insuring a lot of the bank's assets, including securitized mortgages. By taking that risk off the banks' balance sheets, they let the banks take on more risk than they otherwise could have. So maybe AIG wasn't a perpetrator, but it was an enabler.