I am by no means a Bond Trader but I have a basic understanding of how MBIA, AMBAC and the like operate and what they do. I just went to the
MBIA website to see what I could see and noticed that their latest annual report is 2006 and it is 97 pages long! I did find that they claim better than 75% of their insured portfolio is rated A* or better.
AMBAC is the same. The 2007 reports have not been released. I find it interesting that their 10 year stock charts appear almost identical.
MBIA (Symbol MBI)
http://bigcharts.marketwatch.com/quickchart/quickchart.asp?symb=mbi&sid=0&o_symb=mbi&freq=2&time=13AMBAC (Symbol ABK)
http://bigcharts.marketwatch.com/quickchart/quickchart.asp?symb=abk&sid=0&o_symb=abk&freq=2&time=13The confidence rug has been pulled out from under them (or they walked off it, one of the two)
It does not appear that any of the large monoline insurers actually back any GSE issued debt though. The GSE's don't need it because they have the government to point to. So I think (and again, I am NOT a bond trader, nor an expert on this asset class by any means) the answer to your question is "minimal". I say that because even though a bond insurer might have its corporate credit rating downgraded, that alone does not mean that a given basket of GSE issued bonds will be more likely to default. The effect the insurers have on what price a particular bond they insure is traded at is generally a positive. The idea that if an issuer comes into financial difficulty and looks as if it will not be able to make interest payments to bond holders or have an outright default, a company like AMBAC will write a check is a very positive incentive for underwriters when bidding for a new issue as well as for traders to have more confidence when selling or buying a bond on the secondary market. Even though the financial picture of an issuer, be it a city, county, state - what have you - may not have deteriorated, the loss of confidence in the ability of the insurer to pay will force the traders to demand higher yields and as a consequence the price of a given bond will fall. The problems AMBAC, MBIA and their brethren are experiencing is due to them insuring all the Mortgage Backed Bonds issued by the likes of the Countrywides and/or the major underwriters that bought the loans to begin with. Their credibility has been called into question as well as the very real possibility of them becoming insolvent if they have to pony up insurance claims on a massive scale. There are
articles that say they " have a more than 70 percent chance of going bankrupt". I would think neither AMBAC or MBIA knows for sure just how bad it might get for them but I am willing to bet they are doing everything they can to fix the problem.
The impact in the overall bond market is more difficult to specifically determine. Treasuries have seen their prices bid up lately. A 4.25% coupon, 10 year Treasury bond will cost you over $1,040 to buy these days and is yielding about 3.7%. (30 yr Treas. costs over $1,100) Conversely, you can buy a AAA rated 5% coupon 10 year Corporate bond for about the same price yielding a little over 4% The truly well rated bonds will hold their value or go up in price. Those in doubt will see their prices bid down. How large either side of that equation is is anybodies guess.
Here is how it will directly affect those of us that have 401(K)'s, IRA's or other accounts; If you have invested in a bond fund inside one of the aforementioned accounts and that bond fund has in it's portfolio bonds that are being traded lower this week than they were a month ago, the NAV of the fund will suffer, but not really by that much. If the fund manager is forced to rid the fund of downgraded bonds because of the terms of the prospectus, then more problems can set in. Those can be the result of taking a large loss on a position that has lost value considerably. If the fund had a $5,000,000 position in ACME Rubber Chicken 5% 10 year debentures that he bought at par and now can only get $890 a piece for them, that is certainly going to affect the NAV of the fund as well as the yield it is paying. This is REGARDLESS of whether or not the ACME Rubber Chicken Company is has a stellar set of books or not. If the traders value their bonds lower, the fund manager is screwed. It really isn't that serious if you are a longer term investor, though. Most conservatively allocated bond funds don't change in price too terribly dramatically over time. Most trade in a fairly narrow range and only move one or 2 to maybe 3 dollars in price per share. Higher yielding funds are going to have more dramatic swings, just like the bonds they hold.
Remember, bonds are essentially loans that mature at "Par" or $1,000 (With a few exceptions). As long the issuer is able to make the steady stream of interest payments and can pay back the bond holders upon maturity, no loss will be suffered by the holder of the bonds regardless of the price actually paid for them. No one would buy a bond if it had a negative Yield To Maturity at the time of purchase.
*Anything below a "Baa" rating by Moody's or a "BBB" Rating from Standard & Poor's is considered "Below Investment Grade" and the further down the rating list, the more a bond is considered "Speculative". When ratings reach the level of "Caa" They have entered the realm of "Junk" status. The reliability of the ratings assigned various classes of bonds by these rating agencies has been called into question lately but I think they will get their houses in order. They both have an enormous amount riding on their ratings being seen as reliable and accurate.
The full list of ratings given by Moody's looks like this; Aaa, Aa1, Aa2, Aa3, A1, A2, A3, Baa1, Baa2, Baa3, Ba1, Ba2, Ba3, B1, B2, B3, Caa1, Caa2, Caa3, CA, C, D.
Standard & Poor's system looks like this; AAA, AA+, AA, AA- A+, A, A-, BBB+, BBB, BBB-, BB+, BB, BB-, B+, B, B-, CCC+, CCC, CCC-, CC, C.