Researching SEC info, I ran across this Task Force disclosure regarding disclosures on MBS's. I don't know if it has been posted before, so here's the part I found interesting and the site.
Enhancing Disclosure in the Mortgage-Backed
U.S. Securities and
Office of Federal Housing Enterprise Oversight
A Staff Report of the Task Force on Mortgage-Backed Securities Disclosure
IV. Information Imbalance Issues
Some market participants have expressed concern that participants in the MBS markets use information they obtain in their capacities as originators, guarantors and servicers, among others, to select for purchase, sale or retention MBS or underlying mortgage loans that have more favorable characteristics than the average universe of MBS or mortgage loans. Assertions have been made that these entities have an unfair advantage over the marketplace generally in purchasing and selling MBS. In order to evaluate these concerns, it is important to note that at each level of the process of creating and selling MBS, the market participants involved will make certain choices about which mortgage loans or MBS to retain or sell. For example, lenders or pool sponsors select the underlying mortgage loans that they will securitize. Investors may also decide, at the time of a trade that they wish to purchase MBS having certain characteristics.
To review concerns about "favorable selection" or "cherry picking" based on possible information imbalances, it is also important to understand that market participants might view a transaction differently. In order to understand how selection practices may raise issues in the markets, it is helpful to identify the situations that raise a concern for some market participants.
First, some market participants are concerned that when other market participants routinely decide to keep purchased or created MBS in their portfolio, they are relying on information not generally available in making these decisions. In the MBS market, situations exist where a market participant may determine to buy, sell or hold a security or mortgage loan in its portfolio based on information in its possession and not otherwise publicly available. Entities have different reasons for determining to buy, sell or retain securities or mortgage loans, including their knowledge of the product and their business goals and objectives. Any entity involved in originating a mortgage, compiling a pool of mortgages for securitization or creating a MBS may have detailed information about the characteristics of the underlying mortgage loans. Determinations about what securities to keep or sell remain within the control of the originator, sponsor or holder of the MBS.http://www.sec.gov/news/studies/mortgagebacked.htm