Three of the country's largest banks are expected to announce that they are creating a large rescue fund to ease the pain on mortgages securities. The plan, backed by the Treasury Department, is designed to assure investors that it's okay to put more money into the troubled credit market. The new fund will be able to buy as much as $100 billion in bonds and other debt, and will prevent a sudden sell off of assets. That's what happened in August. The cost of mortgages soared and the stock market plunged.