Try this - a large indefinate number (many) of borrowers are 40% underwater.
Lets try this a different way. To be 40% underwater a homeowner would have had to have bought in one of a handful of bubble areas, financed 100%, and have bought within a six month period two years ago.
Thats a small single digit percentage of total homeownership in the US.
Thats not a large indefinite number, many, a lot, or any other characteristic that makes this problem sound worse than it is.
Now...many homeowners in those bubble areas have homes worth 40% less than the value they reached. This does not make them "underwater" in any manner.
In fact, many, if not most, of the homeowners in those bubble areas bought prior to 2004 or in the past year and are either above water or right about at the waterline.
Here's some real personal experience. I bought a house in one of the biggest bubble areas in 2003 and sold it in 2007 for a 24% profit. I bought a house in another major bubble area early in 2007 and its worth about 8% less than I paid for it. The profit I made on the first house is dollarwise twice my paper loss on the second house.
So unless you can point me to some real data that says that a large double digit percentage of US homeowners are ~40%+ underwater in their loan to value calculation...I'm not buying it.
Sorry if you feel like I'm picking on you, but I hate dataless fearmongering. We've got enough problems without people claiming the sky is falling. Especially when its not.
About the only people who got really sporked were people who bought more house than they can afford with a bad loan product over a short time period from 2004-2005, and people who paid way too much for an overinflated house and then couldnt sell their old house and rode the curve down on both.