For the sake of clarity on this discussion:
ALT-A loans typically refer to light or low or no documentation - the term does not designate if the loan is fully fixed or ARM (with some kind of fixed period)
ARM loans can be high quality, low-margin products that will adjust down. Or they can be crappy, high-margin products with a big reset up.
ARM's can be: Conforming, Alt-A, Sub-Prime or Portfolio - all are different.
For the last 50 years, ARM products have been successfully used and have not caused problems. They only adjust incrementally in normal markets if the margin is reasonable.
In fact, for most people, they are a smarter choice than paying a higher fixed rate. Most people only stay in a mortgage for about 4 years on average. The 5/1 ARM (again, a high quality one) saves the average person about $5k to $15k in payments over the 5 year fixed period when compared to a 30 year fixed.
It is only the slew of high-margin Sub-Prime products recently introduced that caused some issues. They were only fixed for 2 years, had big prepayment penalties and high margins, up to 400% higher.
All that being said, it is the equity collapse after an insane up-run of prices that caused the problem. It is not ARM resets.
There are as many people foreclosing on fixed rate loans as ARM's. The problem, no matter what loan they have, is that they are either upside-down or have a high rate - or both.
If they have both problems, they are very high risk to foreclose.
THE ONLY WAY that this problem can be solved is STREAMLINE (no appraisal, rate/term only no cash out re-fi's) just like FHA and VA already allow.
If we do not do this on Conventional mortgages, the foreclosure crisis will continue unabated.
But our shitty Congress and now our Administration is choosing to ignore this reality and has for about 1.5 years now. They prefer Loan Modifications - which are only good in the long run for legal firms and lawyers, no one else.