Level 3 assets at large American investment banks may have “bottomed out”, according to a new report by Moody’s. The stores of these illiquid, difficult-to-value assets often housed many of the most toxic securities that battered banks’ balance sheets during the credit crunch. Any decline in Level 3 assets is considered positive for banks’ credit profiles, Moody’s claims. (For previous coverage of Level 3 assets, click here.)

Somewhat ominously, the ratings agency adds that further falls in Level 3 inventories are unlikely. Although risky and illiquid, these securities feature “attractive yields and wide bid-offer spreads.” Under pressure to boost shareholder returns, it will be difficult for bankers to shun them completely.