no, I don't think that's it.
The problem has arisen because of US deficit financing (living on borrowed money) which has been going on for 20 years and more. The US government has been doing it, relying on loans from other countries, and the US population has been doing it, borrowing money against the value (sorry - price) of their houses which have been going up due to asset price inflation and cheap loans.
As you can't go on for ever, borrowing more and more money and constantly spending more than you earn, a US-sourced financial crash has long been expected, but no-one knew when it would happen.
The "sub-prime loans" market (lending money to people who won't pay it back
at interest rates they can't afford
using as security homes which have been over-valued
and which now can't be sold because no-one will buy them at their inflated prices
and no new lender will lend money against them
) is just a small straw, and there is a lot more balanced on the camel's back.
Today's problem is that no-one knows quite how big the sub-prime problem is, or who's going to be damaged by it. Some US and other funds can be expected to go bust, and some of the US and international banks or investors who foolishly went for a small extra return on a bad debt, will go down with them. There is a hazard in bailing out banks and investors who do foolish things, as it removes the risk and encourages then to do it again. It also punishes the taxpayer, investor or nation who was more sensible but ends up paying for someone else's folly.
As no-one knows where the debts lie, wholesale credit has pretty well dried up, and none of the banks will lend to each other just in case.
Governments and other financial authorities are trying to prop up the banking system to prevent panic which will lead to it grinding to a halt and making things worse.
Probably in a few months time, when the sub-primes defaults have worked their way through, and we see who's still standing, today's crisis will go away.
It does not yet seem to have triggered the US deficit crash which, when it comes, will be a lot worse.
