the ARM in Option ARM basically stands for adjustable rate mortgages. Which plainly means that you have an option to put off payment on the principal. And even an option to choose how much of the interest to pay. This attracts alot of would-be home owners raring to avail of the low interest rates. At first glance this may look like a steal of a deal....
But then the low interest loans don't stay that way forever. After the introductory period, the interest rates go up. And this is where the crash comes in, when borrowers find themselves not being able to make the payments, foreclosure steps in. And this is where the real problem comes, because in 2009, thousands of option ARM loans are resetting, and coming with it a new wave of foreclosures. Much like what happened when the US sub prime loans crashed.
Here's a business week article, if you're interested:
The Next Real Estate Crisis