So who exactly is behind the Walnut Place investors group, which has gone to court to block the much-ballyhooed $8.5 billion settlement of various putback claims? No one seems to know, but the big question is whether there are other investors who ended up with tainted MBS that also feel the settlement is unfair.

If there are many others, the settlement process could get complicated. The Walnut Place group wants to be excluded from the settlement, which it thinks is tainted on several grounds. They argue that the deal is not rich enough for aggrieved bond holders, that the main parties to the settlement are conflicted because they do massive amounts of business with Bank of America (NYSE:BAC), and that settlement was hammered out in secret in a "nonadversarial" fashion.

The latest accusation takes to task the Bank of New York Mellon, which acted as trustee for the bondholders. The group seems to think it was given short shrift by the trustee. Bank of America has argued that the biggest investors had a fiduciary responsibility to their clients and that it would be hard to believe they were remiss in this duty by putting Bank of America ahead of their clients. So where will this go? Judge approval is required for the deal to go forward. The ruling will be eagerly awaited. Until then, the putback uncertainty is back for Bank of America.

For more:  
- here's the complaint courtesy of the WSJ    
- here's a Deal Journal item

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