A company called MarkIt keeps a market index for Asset Backed Securities, which appear to be synonymous with Mortgage Backed Securities after doing a little digging on their site.
I slightly altered their graphic from here by adding historical events.
I'm not completely sure what differentiates the two indexes other than the fact that they are made up of a number of mortgage related funds from different investment houses. The point is the movement, not the actual numbers.
1. It's easy to see that the value of these securities was dropping like a rock until mid-July.
2. Rumors in August and September of a bailout began to surface.
3. Paulson announces the bailout plan to buy up these assets on Sept. 18th. The price jumps.
4. The price reaches its pinnacle about the time that the House passed the Senate version.
5. News snippets start coming out that the Treasury department wasn't actually buying any of these assets, and was moving to shore up bank balance sheets at a number of banks. The price begins to drop.
6. Then on November 12th, Paulson announces that the Treasury isn't going to buy any MBSs. The price drops like a rock.
Analysis - The actions by the Treasury kept these securities from reaching their market clearing price. It will be interesting to see what their price movements are over the next few weeks. Will they plummet? Or will investors move in to snatch up these oversold assets. Given the fact that foreclosures are starting to level off, I wouldn't be surprised.