Mortgage securities rated by Standard & Poor's and Fitch have suffered a similar wave of downgrades.
Today, however, securities rated BB dominate the market -- a 47.5percentt share.
Most high-yield funds concentrate their holdings in securities rated B or BB, but some go as high as AAA, while others go as low as securities with no rating.
How Farmer Mac might fare without its government-issued safety net is less clear, partly because it has never agreed to have its securities rated.
Nor have they taken account of the vagaries of speculative asset markets, mistakes by securities rating agencies and the problems of bond insurers.
Second, we assumed that, if the market ran into difficulties, we could easily adjust and liquidate our positions, especially on securities rated AAA and AA.
Many big investors, such as CalPERS, an enormous public pension fund, do not allow those managing its money to invest in any unrated securities.Scrapping legal mandates to have securities rated has also proved difficult.
Such securities, rated by debt rating agencies before being sold, are crucial for some financial companies to continue lending activities.
BNP's funds invested in securities rated 90% AA or AAA, but that was not enough to allay credit jitters.
Among the assets eligible under the program are private-label residential mortgage-backed securities originally rated AAA and commercial mortgage-backed securities and other asset-backed securities rated AAA.
Investment-Grade Fixed Income Funds: Investment-grade government and corporate bonds, mortgage-backed securities and preferred stock these are securities rated equal to or higher than BBB.
