Economy and General Discussion

When banks held a mortage, as is still the case here in Australia, it was in their own interest to adjust the rate charged for the loan. In fact it was common to note how quickly the banks reacted to a rise in official interest rates, compared to the slow way they dropped in response to an interest rate decrease!  The point I am making is that the charges directly affected their business. Will this now change in the USA now that these debts have been cut up and have many owners, owners who do not have a direct say in the administration of the loan ? Will interest rates automatically change with the change in official interest rates? Will the "ARM"s automatically reset at the appropriate rate? And even if the answer is "theoretically yes", will the practice match the theory? I don't know of the administrative procedures governing these practices but can imagine that obfuscation would be easy and, in the present financial climate, would advantage those who wish to maintain the rosiest picture possible of the mortage market.