View original document

The full text on this page is automatically extracted from the file linked above and may contain errors and inconsistencies.

Statement of Gary Witt
Former Managing Director, Moody’s Investors Service
Submitted by request to the
Financial Crisis Inquiry Commission
June 2, 2010
Opening Remarks
Chairman Angelides and members of the Commission, my name is Gary Witt.
Since 2008, I have been teaching full-time at Temple University in Philadelphia
and no longer have any affiliation with Moody‟s. I am pleased to be able to
participate in today‟s discussion. The opinions I express are mine alone.
The Financial Stability Act that recently passed both houses of Congress expands
the powers of the SEC to regulate of the credit rating industry. The SEC will
determine over the coming months and years how best to use these new powers to
foster more accurate credit ratings. I hope they find our deliberations useful.
I was an analyst and then managing director in the US Derivatives group at
Moody‟s from September 2000 until September 2005 when I was reassigned
within Moody‟s away from CDOs. As one of four managing directors in this CDO
group for 18 months from March 2004 until September 2005, I reported to Gus
Harris. To the best of my recollection, I was responsible for the following areas:
cash-flow ABS CDOs, market value CDOs, Collateralized Fund Obligations
(CFOs), Catastrophe Bonds, and along with Bill May, Structured Financial
Operating Companies.
Rather than delving further into details, I would like to use this time to provide
some context to our discussion of the years preceding the financial crisis.
I‟ll start with an analogy to describe the market players. Picture the organizations
in the financial markets as animals roaming an open plain. The hedge funds were
wolves, hunting in packs, eating what they killed. The investment banks were a
now extinct species of predatory cats, saber-toothed tigers, larger and more
powerful than the hedge funds. The money center banks were the elephants, big,
indestructible, almost a feature of the landscape. And the rating agencies? They
were definitely the goats – specifically, the scapegoats. The analogy is almost
perfect. From the perspective of the other market players, rating agencies fought
over scraps to perform a necessary but lowly task. Just as described in Leviticus,
1

the scapegoats‟ primary function is to absorb the blame for the sins of the
community. They are the animals that everyone loves to hate.
During this financial crisis, many people were quick to assign blame to the rating
agencies. This is appropriate up to a point. We at Moody‟s, along with almost
every major participant in the capital markets, failed to grasp the magnitude of the
housing bubble before 2007; however, as in the parable above, there is a strong
tendency to blame the rating agencies far more than is justified by their previously
mistaken opinions. I believe this tendency results from three related reasons.
The first reason is that people expect too much from ratings. My wife once asked
me, “What good is a rating if it can‟t predict the future?” The answer is that ratings
are tools that help investors manage risk. A bond rating boils down the received
wisdom of the market to a single symbol. Especially for managers of large
portfolios, ratings provide easy organization of a complex risk environment. They
are useful and publicly available to all investors at no charge but investment
decisions should always be based on much more than just a rating.
Second, a rating downgrade is bad news. It‟s bad news for the issuer and bad news
for investors. By definition a rating agency is the bearer of this bad news, the
messenger that is so often shot.
The last reason that large rating agencies like Moody‟s are too popular as
scapegoats is the glaring conflict of interest at the heart of their business model.
They are paid by the issuers they rate. Managing this conflict requires that
Moody‟s balance the competing interests of two groups: investors in Moody‟s
shares and investors in the debt that Moody‟s rates.
During my tenure, management did focus on market share and profit margin so a
question I often ask myself is this. Did the competition among rating agencies in
the securitization markets lead Moody‟s management to over-emphasize the shortterm interests of shareholders? I don‟t know. I can say that it is extremely difficult
to know where the line should be drawn between these two competing interests.
While short-term profits are easy to measure, bond-holders interests are served by
the zealous pursuit of an elusive and distant goal, the right rating.
In my opinion, addressing the conflict between these two asymmetric goals is the
most important task the SEC faces in its regulation of the credit rating industry. I
have described my ideas on addressing this issue in a published article that I
included with my written testimony. Thank you.
2

Written Statement
Please refer to the four Moody‟s methodology papers that I have submitted as
background for my testimony as well as an article submitted to Baseline Scenario,
a blog managed by Simon Johnson and James Kwak.
a) Moody‟s Approach to Rating Multisector CDOs – Sep 2000
b) Moody‟s Correlated Binomial Default Distribution – Aug 2004
c) Moody's Revisits its Assumptions Regarding Structured Finance Default
(and Asset) Correlations for CDOs –June 2005
d) Moody's Modeling Approach to Rating Structured Finance Cash Flow CDO
Transactions – Sep 2005
e) Reforming Credit Rating Agencies – May 20, 2010
Experiences Rating CDOs at Moody’s until Sep 2005
Background
I finished my Ph.D. in Statistics from Wharton in the fall of 1987 and joined
Prudential Securities writing models to value CMOs. As a statistician, my
background in mathematical finance was weak so about one year later, I joined
Citibank to work for an NYU Finance professor and options theory specialist
Georges Courtadon from whom I learned much. I wrote models for valuation and
especially risk management for various option trading desks, especially non-dollar
interest rate options. In 1990, I become a trader on that desk, trading caps, floors
and swaptions in several currencies but mostly DM, Sterling, Yen, and Swiss. In
1991, I moved to London to join a derivatives trading subsidiary of Mitsui Bank as
an interest rate derivatives trader. I continued to work as an interest rate derivatives
trader in London until 1999. I moved back to New York to work for Prudential
Securities again, this time to arrange derivatives transactions in conjunction with
their structured finance underwriting and trading operation. It was at this time
when I first learned about securitization in general and CDOs in particular.

3

Rating CDOs at Moody‟s
While at Prudential I met Jerry Gluck, a Managing Director in Moody‟s CDO
group and several other Moody‟s CDO analysts. Relative to S&P and Fitch, I was
impressed with the transparency and intellectual coherence of Moody‟s approach
to rating CDOs and with Jerry and his staff. I was not fond of the sales aspect of
investment banking so I approached Jerry and he hired me as a Moody's analyst in
the CDO group in Sep 2000. At that time, ABS CDOs were rated according to
the Binomial Expansion Technique (BET) in the attached file "Moody‟s Approach
to Rating Multisector CDOs". The BET model assumes asset defaults are
independent events. A more detailed description of this BET model is given in the
modeling section of my testimony.
After Jerry announced his retirement, I was promoted in March 2004 to become
one of three Managing Directors in the CDO group in NY reporting to Gus Harris
who ran the NY CDO group.
The CDO Rating Process
I would describe the rating process for CDOs during the period March 2004-Sep
2005 as follows. An investment bank analyst or manager would contact the MD in
the CDO group in charge of that CDO type and describe a planed CDO
underwriting for a month or two hence to request that Moody‟s rate it. During this
time period, a rating application describing the rating fees would be sent unless the
MD was confident that the investment banker was already aware of the details of
Moody‟s rating application. The MD would assign a quantitative and a legal
analyst to the CDO based on a number of factors, the most important being
availability and expertise. The two analysts‟ contact details would be given to the
investment bank analysts.
The interaction between Moody‟s analysts and the investment banking analysts
would be through a series of conference calls, on-site visits, and email information
exchanges intended to convey all the information necessary for the Moody‟s
analysts to rate the CDO. The analysts would work independently unless/until
there was an issue needing to be discussed with the relevant MD. Sometimes the
relationship between the banking and rating analysts was strained. The investment
banking analysts tended to be highly motivated, ambitious people expecting to get
their own way. Banking analysts would sometimes use deceptive or intimidating
tactics to achieve their goals. Managing these banking relationships took up a great
deal of time and focus.
4

In addition, our analysts would speak with and visit the Collateral Manager if no
one had done so in the recent past. The rating process would culminate in a rating
committee usually chaired by the MD. A rating letter would be sent to the
arrangers just prior to the closing date of the CDO that would specify exactly the
ratings of all the rated securities and a definition of those ratings.
Rating Decisions were based closely on a transparent methodology
The rating decision taken during the rating committee was based largely on
modeling results. For cash-flow ABS CDOs, the expected loss of each tranche was
calculated under several different combinations of interest rate scenarios, default
timing scenarios and prepayment scenarios for a total of about one hundred
different expected loss numbers. There were specific guidelines for converting
those expected loss results into ratings. Moody‟s CDO rating methodology was
published on its website and freely available to all interested parties. As such it was
very transparent. The methodology used to produce these expected losses (and
hence the ratings) was based on public information.
It is important to understand that most groups within rating agencies do not have
methodologies that are transparent or even objective to the extent that the CDO
group at Moody‟s did during my years there. I believe the benefits of a transparent,
objective rating methodology outweigh the costs but there are good reasons for
opinions to differ on this point. If issuers know what the methodology is, they will
structure their issues to conform to it. Also, the fact that CDOs are derivative
instruments makes a transparent, objective policy possible because publicly
available ratings of the assets are the most important inputs necessary to determine
the rating of the CDO notes. Further, a transparent methodology can be a
straightjacket as it reduces flexibility in many ways. For instance, changes in rating
methodology are more difficult because of its immediate and obvious consequence
for outstanding ratings.
The benefits of a transparent methodology are that it provides strong rating
discipline to the rating agency. It increases accuracy as any deviations from
published methodology are likely to be caught by other market participants.
Letting in the sunlight through transparency allows the rating agency to benefit
from the suggestions of other market players as to what changes in rating policy
are warranted. It facilitates an efficient issuance pipeline as market players can
make reasonable estimates of ratings themselves and plan accordingly. It reassures
other market players of the integrity of the rating process by removing even the
appearance of favoritism or bias in rating decisions.
5

Did Rating Analysts and Investment Bank Analysts work too closely?
There are some misconceptions and legitimate concerns that one often reads in
press in relation to this process. It is often stated that rating agencies acted as
consultants or structured CDO transactions. During my 18 months as an MD at
Moody‟s, I know of no cases of analysts being paid as consultants to structure
deals. On the other hand, concerns that rating analysts and investment banking
analysts worked too closely together prior to the issuance of securitized debt is a
legitimate concern. Typically, it was stated in the offering documents of these
CDOs as a condition of issuance that each tranche achieve a certain rating from a
certain rating agency. Obviously, the only way the underwriter could include the
rating of each tranche in offering documents as a condition of issuance was if the
underwriter already knew the rating prior to issuance. On complex securitization,
allowing such language to appear in the offering documents guarantees that
investment banks and rating agencies will work closely together during the
structuring phase of the transaction. The SEC could prohibit such language in the
offering documents of these securities and could require a certain waiting period
(e.g. four weeks for long dated securities) until ratings are issued. They could
allow for a rating agency to be engaged prior to issuance so that investors would
know who would rate the issue but not the actual rating level. The downside of
such a policy is that investors would not know the rating of securities on the
offering date and would bear an additional “rating risk.” This would force investors
and underwriters to rely less on ratings in the initial offering period. It would also
be very helpful in combating ratings shopping (addressed under Market Share
Considerations).

Staffing decision made as a result of pressure from a bank
When Rick Michalek testified on April 23, 2010 before the Senate‟s Permanent
Subcommittee on Investigations that “I was told by a different managing director
that a CDO team leader at Goldman Sachs … would prefer another lawyer”, he
was referring to me as the unnamed Moody‟s managing director.
In my opinion, Rick Michalek was an exceptionally thorough legal analyst. His
zealous document reviews were an added expense for investment banks who hired
top law firms as transaction counsel with high hourly fees. It was my
understanding that this behavior (exceptionally thorough document reviews that
resulted in high legal fees being charged to investment banks) had led to a personal
reprimand from Brian Clarkson, then head of structured finance. Rick confirms this
in his testimony writing about a meeting with Brian Clarkson “the primary
6

message of the conversation was plain; further complaints from the „customers‟
would very likely be abruptly end my career at Moody‟s”
To the best of my recollection, in late 2004 or early 2005, I received a request from
a CDO structurer at Goldman Sachs that Rick not be assigned to further Goldman
Sachs CDOs for the next year. I was told that failure to comply with their request
would result in a phone call to one of my superiors. I was concerned that this could
possibly result in Rick‟s dismissal. I discussed the situation with Rick and we both
agreed that the best course of action was to comply with Goldman‟s request. My
thinking was that if I needed Rick‟s expertise on any specific issues on later
Goldman deals, as long as he was employed by Moody‟s, I could at least have him
review sections of their documents on an as-needed basis without his formal
assignment to the transaction. Rick was my friend and I wanted to protect him but
more importantly, he was an excellent resource for document review on complex
or deliberately misleading deal documentation and I needed to retain his expertise.
Liquidity Puts for Commercial Paper Issued out of CDOs
Watching some testimony of previous FCIC hearings, I was reminded of some
experiences I had as an analyst and MD in the CDO group that I thought might be
of interest to the commission. These events occurred over five years ago but this is
what I remember.
In late 2003 I worked with Rick Michalek on two CDOs underwritten by Citi that
were very early versions of high-grade CDOs that issued a large volumes of P-1
rated commercial paper. I was of the opinion then as an analyst and later as an MD
that the long-term Aaa rating on ABS CDOs did not imply that those securities
would remain liquid throughout their lifetime. My perspective was that a CDO
could only issue P-1 rated commercial paper if a P-1 counterparty made a binding
commitment to purchase the CP if no one else would. I was very conscious of the
importance of money market funds to the financial system, the importance of CP to
money market funds, and the importance of a P-1 rating via Rule 2a-7 as a
criterion for collateral in money market funds.
The solution from Citi and other banks was to embed a “liquidity put” in the
underlying transaction documents. I believed this was similar to Asset-Backed CP
conduits although I was not that familiar with ABCP conduits at the time. There
seemed to be an emphasis on the part of the banks to distinguish between these
liquidity puts and an outright credit guarantee of the underlying Aaa CDO
tranches. I suspected it was referred to as a liquidity put instead of a credit
7

guarantee to minimize the apparent risk to Citi although I could see little difference
between the two.
I found the documentation concerning the liquidity puts on these transactions to be
impenetrable. I was very concerned that the complexity of the documents could
conceal contingencies under which Citi would not be obligated to purchase CP in
the event of a failed auction. As this would result in a payment default to a CP
investor, my estimation of the value of Rick‟s document review expertise and
dogged determination increased dramatically as he was able to effectively review
these complex agreements.

Market share considerations in ABS CDOs
In my early years at Moody‟s as rating analyst I was assigned CDOs to rate and my
focus was narrow. Follow the methodology and get the right rating. After I was
promoted to managing director and had to deal with budgets and staffing I began to
see a bigger picture. There was a legitimate need to consider the interests of
shareholders in making a profit. As an MD, my marching orders as I understood
them were to first get the ratings right and then second to maximize profits. I was
told that it was acceptable to lose ratings and have a declining market share as long
as you had a reason. If we lost ratings because the other agencies ratings were
higher than ours and I believed that we were right and they were wrong, I needed
to be able to articulate to my superiors the reasons why we were right. If the
situation persisted, I needed to publish the explanation of why our ratings were
right and our competitor‟s ratings were wrong.
As an example, at Moody‟s the CMBS group changed its methodology to be more
conservative at the beginning of the financial crisis. Tad Phillip from the CMBS
group advised Brian Clarkson and Noel Kirnon that he believed the conditions in
the commercial property market would deteriorate and that Moody‟s should
increase its rating standards. They all expected to suffer lost market share and
lower rating revenue and they certainly did. There was a rapid loss of market share
(my recollection is their market share dropped from 75% to 25%) in spite of the
fact that the financial crisis had already begun. My recollection is that the press
hardly noticed or commented. This is an important story that illustrates that
Moody‟s management was willing to forego large amounts of lost revenue in order
to get to the right rating. On the other hand, this CMBS story illustrates how it was
difficult to make changes in methodology based on forward looking concerns
about the markets as Tad was able to point to current market dislocations as
8

evidence. Methodology almost always depended on past data as the only
unassailable objective source of information and this is an exception that illustrates
the rule.
Coping with low market share in mezz RMBS
I received emails with attached spreadsheets on a periodic basis detailing CDOs
rated by S&P and/or Fitch but not by Moody‟s. I was often asked to research the
reasons why Moody‟s did not rate these CDOs. As 2004 progressed into early
2005, to the best of my recollection, there were a number of ABS CDOs not rated
by Moody‟s due to the fact that Moody‟s did not rate several of the underlying
mezzanine RMBS tranches, in which case the CDO would have received a lower
Moody‟s rating due to our notching policy. The issuer might be able to avoid a
lower rating if the issuer paid extra fees to obtain rating estimates for those
tranches not previously rated by Moody‟s. Because the process of obtaining rating
estimates was expensive, time-consuming and uncertain as to outcome, many
issuers did not obtain Moody‟s ratings when large percentages of the underlying
collateral were not Moody‟s rated.
This was a source of concern for my direct superior Gus Harris. I recall visiting
with him the offices of one particular issuer, C-Bass on more than one occasion
where we would discuss ways that Moody‟s could reduce the cost and speed the
process of obtaining the necessary rating estimates of those tranches unrated by
Moody‟s.
During that time period interest rates were rising. Three month labor started 2004
at 1% and rose to 2.5% by the end of 2004 and 4.5% by the end of 2005. Although
I was not in the RMBS group at Moody‟s and did not follow these events on a
daily basis, it is my understanding and recollection based on press reports from that
time period and from other market participants that the primary reason that
Moody‟s did not rate the underlying mezzanine RMBS tranches was that S&P did
not update its interest rate assumptions even after rates began to increase. This had
the effect of making S&Ps ratings on mezzanine RMBS higher than Moody‟s.
After some criticism, S&P did update its interest rate assumptions in the middle of
2005 and Moody‟s market share in mezzanine RMBS rose to a substantially higher
level. I left the CDO group in Sep 2005 but I have seen evidence that Moody‟s
market share in ABS CDOs increased later in 2005, 2006 and 2007 as its share in
the underlying RMBS collateral increased.

9

Ratings Shopping
A very legitimate issue for concern by regulators is ratings shopping. It was
interesting to hear Secretary Geithner‟s comments about regulatory arbitrage at the
FCIC hearing on the Shadow banking System. He pointed to the case of
Countrywide choosing its own regulator by establishing itself as a thrift. The
situation with ratings and rating shopping in the securitization markets is much
worse. Underwriters and/or issuers can and do change rating agencies at any time.
They are also more than willing to use the threat of dropping an agency from a
transaction to try to obtain leverage on whatever issue is of concern to them. The
situation is exacerbated by the fact that most investors hardly make a distinction
between the better known agencies viewing the ratings and the rating agencies as
interchangeable (as a Moody‟s employee I was often mistakenly referred to as
working for S&P by other market players, sometimes when they were visiting our
offices). Issuers almost always opt for the highest rating obtainable period. The
previously mentioned example of the CMBS group changing its methodology to be
more conservative at the beginning of the financial crisis is of course a classic
illustration of rating shopping. In spite of the fact that the financial crisis had
already begun, issuers still went with the highest rating with apparently little regard
for quality. Issuers only priority is to offer debt on the most favorable terms
possible. An article in the Wall Street Journal just last week by Serena Ng
described how the practice is alive and well. The important point to understand is
that no single rating agency can address this problem. It can only be addressed
through regulation. The Credit Rating Agency Reform Act of 2006 probably made
the situation worse with its focus on increasing competition among rating agencies
without any compensating mechanism to combat rating shopping. More recently,
the amendment to the Financial Stability Act offered by Senator Franken may help
but it too must be monitored for unintended consequences. If the SEC or its
appointed board promote any particular agenda by dictating which rating agency
rates which transactions, rating agencies will seek to issue ratings in a way that
conforms to that perceived agenda.

Overview of Management Responsibilities as a Team MD in CDOs: Mar04-Sep05
The previous sections have mostly described the role of a managing director in the
new issue rating process for CDOs. During this time period, MDs had many other
responsibilities.
Along with Bill May and Yuri Yoshizawa, I was a Team MD in the US
Derivatives Group. We reported to a Group MD, Gus Harris who headed US
10

Derivatives, who reported to a Senior MD heading Global Derivatives, Noel
Kirnon, who in turn reported to the head of Structured Finance, Brian Clarkson.
During this time, all three of these executives above me in the hierarchy had
offices on the eighth floor of 99 Church St as did Bill, Yuri and I and the most of
the US Derivatives Team of about 80 analysts. The TMDs each had 15-20 direct
reports and no staff. We had no independent research staff and no administrative
staff. I shared a secretary with many other people and her time was often allocated
to the more senior managers on my floor. The management structure was still
totally flat at my level but as we grew there was a great need to create another level
of hierarchy which I worked toward throughout my eighteen months with the
appointment of team leaders who could substitute for me as committee chairman in
their area of expertise when needed.
Transaction volume was growing by 50% per year and in some areas faster. During
this time, we were responsible for methodology and monitoring of existing
transaction in our areas. During my eighteen months as an MD in CDOs I spent a
huge amount of time working on methodology because the ABS CDO market
especially was in transition from multi-sector to single sector transactions which I
felt clearly implied a need to update our methods.
The problem of recruiting and retaining good staff was insoluble. Investment banks
often hired away our best people. As far as I can remember, we were never
allocated funds to make counter offers. Basically we had a few seasoned
quantitative staff. We compensated by hiring large numbers of junior staff to flesh
out our ranks but inexperienced people had to be trained. Then, they became prime
targets to be hired by I-banks. It was extremely difficult for us to hire experienced
quantitative analysts. One very frustrating experience I had was in trying to hire a
mid-thirties quant from Wharton whom I knew personally to be extremely good
but unhappy at the consulting firm where he worked. He would have been a big
asset for the CDO group but my boss refused to pay an extra $20,000. He was
hired away by an insurance company for $20,000 more than we offered him. We
were better able to attract good legal staff because working conditions at the law
firms were difficult, so some experienced lawyers were happy to work at Moody‟s.
There had been across the board salary raises just prior to my coming to Moody‟s.
Apparently management was determined not to repeat that mistake. Our complex
product line was increasing the importance of experienced quants. We had almost
no ability to do meaningful research. Our market was growing rapidly. In my
opinion, penny-pinching on salaries in a group with very large profit margins but
these serious staffing issues was poor management.
11

I was also in charge of several other segments of the CDO market but the biggest
time killer was the Structured Financial Operating Companies (SFOC). These were
a mixed bag consisting of several existing Derivative Product Companies
established in the 1990s by various banks around the world to use collateral
posting requirements to create Aaa counterparties to offer interest rate or currency
derivatives. A new type of SFOC was the Credit Derivative Product Company that
would perform the same counterparty rating enhancement for offering credit
derivatives. These were more complex that the older DPCs and were only
emerging so we had to grapple with many novel risks. There were several other
types of SFOCs that demanded my time as well as the other product lines I
mentioned in my opening remarks.
Another problem was that senior people from investment banks often called with
complaints or requests. We were expected to address their concerns if at all
possible. Senior bankers generally had relationships with our superiors and would
call them if unsatisfied. I, and I believe my two colleagues as well, were in a
reactive mode almost all the time. It was a very difficult working environment that
left little time to reflect or to prepare for the future.
Modeling Considerations
Note: There is additional detail about Moody’s modeling in the final section of this
written testimony which is a rebuttal to an article posted on Bloomberg.
The FCIC preliminary staff report “Securitization and the Mortgage Crisis” dated
Apr 7, 2010 contains an accurate depiction of the construction of a CDO in Figure
3 on page 9. A pool of BBB RMBS bonds are used as a collateral pool against
which CDO liabilities are issued. RMBS tranches in the middle of the capital
structure rated A or BBB were referred to as mezzanine bonds, hence the term
mezzanine ABS CDOs.
ABS CDO liability ratings depended heavily on ABS ratings
Almost all Moody‟s CDO rating methodologies were derivative in the sense that
the most important input was the rating on the bonds in the collateral pool. The
purpose of the methodology was to transform this pool of asset ratings into ratings
on each of the CDO liabilities. The first step in this process was to convert each
collateral bond rating into a default probability via standard tables compiled from
Moody‟s long-term rating performance.

12

Using the BET to calculate expected loss and rate CDOs
When I joined Moody‟s in Sep 2000, ABS CDOs were rated according to
the Binomial Expansion Technique (BET). The BET depended first on the ratings
of the underlying assets and second on a measure of portfolio concentration called
the diversity score. The BET modeled the actual portfolio with a representative
portfolio. The default probability for each bond in the representative portfolio was
the average default probability of the actual portfolio. For a BBB portfolio the
default probability would about 5%.
How can $100mm of BBB bonds support a $70mm AAA CDO rating?
The number of bonds in the representative portfolio was the diversity score. To be
more precise, the diversity score was defined as the number of independent bonds
in the representative portfolio. The basic idea was to represent a large number of
correlated bonds with a smaller number of uncorrelated or independent bonds. As
an example, consider a portfolio 100 BBB corporate bonds from different
industries each with a notional of $1,000,000 and a default probability of 5%.
There is a CDO issued using this collateral. The senior bond gets first priory on all
money from these $100,000,000 worth of bonds. It has a notional of $70,000,000.
Using a BET approach we might model this portfolio as 10 independent bonds
each with a notional $10,000,000 and a default probability of 5%. For simplicity
assume default results in a total loss. Then the probability that the senior bond
defaults (does not pay in full) equals the probability that more than three of the
$10mm model bonds default. Here are default probabilities of the model portfolio.
10 independent bonds each have 5% chance of default
Number of defaults
0
1
2
3
4
5
6
7
8
9
10

Probability
59.87%
31.51%
7.46%
1.05%
0.10%
0.01%
0.00%
0.00%
0.00%
0.00%
0.00%

13

Since there is such a low probability of default for each bond (5%), there is
actually a 60% probability that no bonds will default. From the table we can see
that the probability that more than three bonds default is
0.10% + 0.01% = 0.11%
That is about 1 out 900 which would be a Moody‟s rating of about Aa2.
If we increased the diversity score, the number of independent bonds to 20 each of
$5mm and repeated the exercise to calculate the probability that more than six of
these bonds default, the probability would be 1 out of 30,000, clearly Aaa. That
would be accurate if we believed that ten representative bonds understate how
much diversification we have in our portfolio.
As the example illustrates, probabilities can easily be calculated for differing
default percentages of the collateral pool. With these probabilities and some further
assumptions about loss given default, the expected loss of each tranche of the CDO
liabilities could be calculated and the rating determined. The expected loss is
simply the probability of each loss scenario times the loss for that tranche. The loss
for each tranche is calculated from the collateral loss by a separate model of the
cash-flow waterfall or priority of payments that determines how cash from assets is
allocated among the liabilities in each period.
The BET was wonderfully simple but it depended heavily on the calculation of the
diversity score. For the first CDOs rated with this method, emerging market and
high yield debt (aka junk bonds) during the period 1995-2000, the diversity score
was calculated by dividing bonds into groups and counting how many bonds were
in each group. Within each group the contribution to diversity score increased at a
decreasing rate and was capped at five so that maximum diversity score
contribution from a single group was five. For corporate bonds the groups were
industries and the maximum possible diversity score was the number of industries
times five. There were about 30 industries but the typical high yield CDOs had a
diversity score between 40 and 50.
Multisector ABS CDOs
After the Asian financial crisis and LTCM debacle, credit spreads on risk assets in
1999-2000 remained wide. Investment banks held inventories of highly rated
collateral with unusually wide spreads and were seeking a solution of how to sell
them. It was in this environment that the first ABS CDOs were issued and rated.
They were tellingly referred to as multisector CDOs because emphasis of early
14

ABS CDOs from this period was on constructing a diversified portfolio of ABS. A
typical ABS CDO from 1999-2002 contained 33% RMBS, 25% CMBS, 10%
Manufactured Housing (MH), and one-third from securitizations of credit cards,
auto loans, student loans, aircraft leases, equipment leases, mutual fund fees and
other more exotic categories of receivables. See the paper I submitted with my
testimony "Moody‟s Approach to Rating Multisector CDOs".
This paper continues to use the BET as the basis for modeling defaults. One
innovation is an alternative method for calculating the diversity score, often
referred to as the two-moment method because the representative portfolio is
chosen to match the mean and the standard deviation of the default distribution on
the actual portfolio. This two-moment matching scheme is possible because default
correlation assumptions were introduced at that time.
Here is the first paragraph in the section Assumptions about Default Correlations.
“In order to apply the alternative diversity score, we must make assumptions about
default correlations. Implicitly, any measure of diversification relies on such
assumptions. Because there have been very few defaults among structured
instruments, our default assumptions are based on a priori views as to the extent to
which different asset classes are related.”
My understanding was that the correlation assumptions were educated guesses
derived from discussions with analysts in these various securitization areas. Little
data was available so little data was used. In any event, it was these correlations
that determined the diversity score for ABS CDOs at Moody‟s until the second half
of 2005. They were some slight modifications (as I recall to HEL) over these years
but essentially these original default correlation assumptions were used. The Sep
2000 paper shows calculation of the diversity score but does not list correlations.
The table below is based on the best information I have at this time but I believe it
to be accurate for investment grade assets in ABS CDOs during 2004-2005.
Correlations between below investment-grade assets were slightly higher.
HEL- Home Equity Loans
MH- Manufactured Housing
Resi A – Residential A, later called prime
Resi B&C – Residential B&C, later called Alt-A and sub-prime
CMBS – Commercial Mortgage Backed Securities, this is the correlation
assumption for the Conduit category within CMBS.
Mut Fund Fees – Mutual Fund Fees
15

Indicative Default Correlation Assumptions for ABS CDOs
HEL
MH
Resi A
Resi B&C
Credit Cards
CMBS
Aircraft Lease
Mut Fund Fees

HEL
MH
14.0%
3.0%
3.0%
14.0%
10.75% 3.00%
3.0%
10.75%
7.5%
7.5%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%

Resi A
10.75%
3.0%
14.0%
3.0%
7.5%
0.0%
0.0%
0.0%

Resi B&C
3.0%
10.75%
3.0%
14.0%
7.5%
0.0%
0.0%
0.0%

Cards
7.5%
7.5%
7.5%
7.5%
14.0%
0.0%
0.0%
0.0%

CMBS
0.0%
0.0%
0.0%
0.0%
0.0%
12.0%
0.0%
0.0%

Aircraft
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
14.0%
0.0%

MFFee
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
14.0%

Explanation of Table Correlations
For example the correlation between two Resi A bonds was 14%.
The correlation between a Resi A bond and a Resi B&C bond was 3%.
Higher correlations implied lower diversity scores.
In general the more bonds in the collateral pool, the higher the diversity score.
Here is a rule of thumb to understand the relationship between the default
correlation and the diversity score. If D is the diversity score and ρ is the
correlation, then , in the limit as the number of identical and identically correlated
bonds gets large, the maximum possible diversity score is
D = 1/ρ.
So a portfolio of 100 Resi B&C bonds would have a diversity score of no more
than 7 because 1/0.14 ≈ 7.
Again, the table above is not a definitive source for these correlation assumptions.
Most ABS CDOs had correlation assumptions built into their deal documentation
which was used by the trustee to calculate the diversity score to monitor its
adherence to the diversity score test. Typical diversity scores for these multi-sector
ABS CDOs were 16-20. Credit quality was typically in the Baa1-Baa3 range, i.e.
these were mezzanine ABS CDOs. These deals were in the range of $200mm$500mm and often had over one hundred separate bonds in the collateral pool.
After the attacks on September 11, 2001 and the bursting of the tech bubble,
various of these asset classes experienced large credit losses: notably aircraft
leases, mutual fund fees and manufactured housing. By the time I was promoted to
MD in early 2004, the reaction of buyers in the ABS CDO market was to
concentrate more heavily on either residential or commercial mortgages. ABS
16

CDO become more concentrated
CDOs increasingly became concentrated in either RMBS or CMBS with a
corresponding drop in diversification. The average diversity score for Mezzanine
ABS CDOs rated at Moody‟s dropped from 17 in 2003 to 14 in 2004.
For modeling purposes in these ABS CDOs, the BET drastically reduced the
number of assets to account for the fact that they were increasingly correlated. I
have always believed that simple models are best, especially when used by large
numbers of people not accustomed to using complex mathematical models. The
BET was very useful in this way but for these high correlation, low diversity
CDOs, the gap between the actual portfolio and the representative portfolio was
becoming too wide. The assumption of independence in the BET was becoming a
problem as the portfolios we were modeling became more highly correlated.
Further the trend toward concentrated portfolios was continuing.
The obvious alternative was to use the normal copula to simulate the loss
distribution of the collateral pool. Other rating agencies and investment banks were
rapidly moving to adopt it. It did not depend on the assumption of independence. I
was not a fan of the normal copula for several reasons. It depended on the
multivariate normal distribution which was famous among statisticians for having
thin tails. This problem was especially pronounced for high-grade CDOs which
were becoming more popular. These were ABS CDOs that had an average rating in
the Aa2-A2 range. I did see the normal copula as an improvement over the
assumption of independence but I was wary of simulations in the context in which
we ran our business. It was too hard to catch calculation errors as simulations vary
with each implementation. I wanted to retain a closed form distribution like the
BET except with correlation built explicitly into the model.
In spite of my difficult work environment, I worked hard on weekends and late at
night to develop just such a model. My goal was to find a way to assume a uniform
portfolio including uniform default correlations to determine a valid, useful
portfolio default distribution. I wanted to keep the diversity score and default
correlation framework but introduce correlation explicitly into the model. I
achieved this goal. I wrote and was allowed to publish on Moody‟s website in
August 2004 the paper "Moody‟s Correlated Binomial Default Distribution."
It includes a measure of correlation in the model and so addresses what I viewed
as the major drawback of the older BET methodology, its assumption that assets
are independent.

17

The correlated binomial with default correlations as described in this August
2004 paper was used for a new type of CDO, Trust Preferred (TRUPS) CDOs but
it was not adopted as Moody's methodology for ABS CDOs. In theory, we would
have used it for CDOs with a diversity score of less than ten but this rarely
occurred.
The Aug 04 paper contains a comparison of expected losses for the BET versus the
correlated binomial and the normal copula. All calculations are based on the old
default correlations assumptions from the Multisector paper. The normal copula
expected losses are calculated by converting from default correlations into copula
(or asset) correlations via the following scheme. For a given default probability,
use the default correlation to calculate the joint probability that two assets default.
Then, choose the copula correlation that gives the same joint probability of two
asset defaults. Using this scheme, for the range of default correlations and default
probabilities encountered in these applications, as Table 4 shows, the expected
losses are very similar for the correlated binomial and the normal copula. The
expected losses at the Aaa level for the BET were much lower indicating that the
BET would give higher or less conservative ratings. It should be emphasized that I
did not have an agenda to lower our ratings. I wanted to use a more accurate model
for concentrated portfolios but did not have a premonition of the house price
declines that were still more than two years in the future.
The more widely known methodology, the Normal Copula was instead adopted. I
accepted this decision as it was reasonable. I believe it to be an improvement over
the BET for highly concentrated CDOs. In June 2005, after the research by various
analysts and after various committee meetings chaired by Noel Kirnon, then head
of global CDOs, the methodology and parameters in the paper "Moody's Revisits
its Assumptions Regarding Structured Finance Default (and Asset) Correlations for
CDOs" based on the normal copula were adopted. It is my belief based on what I
know, that the new correlations were based on a more systematic study of data than
the earlier correlations from the Multisector paper of Sep 2000 - mainly because,
by 2005, more data was available. My understanding is that this paper defined the
ratings of ABS CDOs until at least Sep 2007.

18

Aaa Mezz SF CDO Spreads to Libor
80
70
60
50
40
30
20
10

4-May-05

4-Mar-05

4-Jan-05

4-Sep-04

4-Nov-04

4-Jul-04

4-May-04

4-Mar-04

4-Jan-04

4-Nov-03

4-Sep-03

4-Jul-03

4-May-03

4-Mar-03

4-Jan-03

4-Nov-02

4-Sep-02

4-Jul-02

4-May-02

4-Mar-02

4-Jan-02

4-Nov-01

4-Sep-01

4-Jul-01

4-May-01

4-Mar-01

4-Jan-01

0

Credit Spreads on Mezzanine ABS CDOs from 2001 until June 2005

This graph is included to provide some perspective on the market for Aaa ABS
CDOs at the time that these correlations were updated. Spreads on Aaa mezzanine
ABS CDOs had been declining steadily for two years.
This June 2005 paper does include the correlation assumptions in it. A comparative
sample is given the below table. With the benefit of 20/20 hindsight the
correlations in that paper should have been higher. The same statement is true for
the default correlation assumptions used in the BET. It would have been difficult to
justify raising correlations substantially higher given the historical data and trends
in CDO spreads in the market at the time shown in the graph above.
In reference to the following table, it must be emphasized that these are normal
copula correlations and not default correlations. Direct comparisons between the
two are not meaningful. The valid comparison is to consider the impact on
expected loss calculations for CDO tranches at various level of subordination
where the collateral portfolio has been categorized using both the default
correlation and copula correlation approaches.

19

Indicative Copula Correlation Assumptions for ABS CDOs - June 2005 –
Assumes One Year Vintage Penalty (one year apart - not the same year)
Prime
Midprime
Subprime
MH
Credit Cards
CMBS
Aircraft Lease
Mut Fund Fees

Prime
22.0%
4.0%
4.0%
4.0%
3.0%
1.0%
1.0%
1.0%

MidP
4.0%
24.0%
4.0%
4.0%
3.0%
1.0%
1.0%
1.0%

SubP
4.0%
4.0%
27.0%
4.0%
3.0%
1.0%
1.0%
1.0%

MH
4.0%
4.0%
4.0%
47.0%
3.0%
1.0%
1.0%
1.0%

Cards
3.0%
3.0%
3.0%
3.0%
26.0%
1.0%
1.0%
1.0%

CMBS
1.0%
1.0%
1.0%
1.0%
1.0%
21.0%
1.0%
1.0%

Aircraft
1.0%
1.0%
1.0%
1.0%
1.0%
1.0%
40.0%
1.0%

MFFee
1.0%
1.0%
1.0%
1.0%
1.0%
1.0%
1.0%
40.0%

This categorization was done for two portfolios in the Sep 05 paper described
below “Moody's Modeling Approach to Rating Structured Finance Cash Flow
CDO Transactions”. Using the example portfolio Diversity Score 10 from table 4
with a recovery of 30% and a default probability of 3.5%, I found that the expected
loss using the appropriate stress for the BET was higher at 19% but lower further
out in the tail of the portfolio. So the correlated binomial using the MAC to mimic
the normal copula as described in the following paragraph would be more
conservative than the BET at the Aaa level for this mezz portfolio. More detail
about the assumptions used in this example were provided to the FCIC staff.
Subordination

Norm Copula/CBM

BET E(Loss)

Level

E(Loss)

with Stress Levels

19%

0.0191%

0.0200% Aa1 Stress

20%

0.0148%

0.0123% Aa1 Stress

21%

0.0113%

0.0050% Aaa Stress

22%

0.0087%

0.0044% Aaa Stress

23%

0.0067%

0.0037% Aaa Stress

I formally left the CDO group in Sep 2005 after completing work on the paper,
“Moody's Modeling Approach to Rating Structured Finance Cash Flow CDO
Transactions” It was written by a seasoned quantitative analyst and myself to allow
Moody‟s analysts to use the simpler Correlated Binomial with CDOROM to rate
CDOs in a way that would very closely mimic the rating from the Normal Copula
method. It describes an algorithm to determine a normal copula asset correlation
(Moody‟s Asset Correlation or just MAC) that is converted to a default correlation.
20

The default correlation is then used in the correlated binomial to replicate the loss
distribution from the normal copula as specified in the June 2005 paper. Cash
ABS CDOs were rated using this scheme after I left the CDO group. The idea was
that the MAC would be a single measure of portfolio concentration similar to the
diversity score. Also, the correlated binomial was a closed-form distribution with
only three parameters and so was much easier to use than a normal copula
simulation. So after September 2005, Moody‟s did use the correlated binomial to
rate ABS CDOs as a computational convenience but only in a way that guaranteed
that the expected loss and hence the rating would replicate the normal copula.
Departure from the CDO group and aftermath
In the second quarter of 2005 I began to feel that my responsibilities were too large
relative to the authority or the resources I had to address them. The pressures of
revising methodology while running the group at a time of sharply rising rating
volumes made me think more about how thin my resources were relative to my
responsibilities. I did not feel that we were getting the ratings wrong, but I did
think that we were not allocating nearly enough resources to getting the ratings
right.
I called a university in Texas that had offered me a teaching job in the past. I
accepted their invitation to visit the campus, meet some new people and give a
lecture. They again offered me a job. I told my superiors at Moody‟s I was
considering this job offer in late April or early May 2005. They requested that I
decide quickly. The school could not match their previous offer from years before
as I anticipated so in the end I turned them down and stayed at Moody‟s but
assumed that management‟s trust in me was permanently diminished.
In the summer of 2005, I was asked by the head of Structured Finance at that time,
to leave the CDO group and work on unspecified new products. This move was
perceived by all who knew me as a demotion, 15 direct reports to zero, many tens
of millions in revenue to manage down to zero. Even so, I was happy to agree to
his request. I was relieved to be absolved of the responsibilities in the CDO group.
I suspected that the head of Structured Finance would begin to ignore me but to my
surprise, when I pitched him the idea of Operational Quality ratings for hedge
funds, he was very supportive. With his support I hired a small but solid staff and
built the OQ ratings into a successful business. With this success, I began to
acquire additional responsibilities for asset manager ratings. My last nine months
21

at Moody‟s I was in charge of 25-30 people worldwide rating hedge funds, mutual
funds and money market funds.
During this time I had one last interaction with the CDO group. By 2007, Eric
Kolchinsky had taken over my old job as MD in charge of ABS CDOs. Years
before, Eric had been an analyst working for me and he began to confide in me his
concerns about the mortgage market and its implications for ABS CDOs. As 2007
progressed he become much more worried but complained that his superiors did
not share his concerns. In September I encountered him one day in a grave mood.
He said that he knew from a senior RMBS analyst that large scale downgrades in
RMBS were imminent but that he feared his supervisor would force him to
continue rating ABS CDOs that would then have to be immediately downgraded. I
advised him to inform the head of credit policy, Andy Kimball. He was concerned
about retaliation so I volunteered to contact Andy myself. Andy and I traded
emails where I informed him of the situation and sent him details of upcoming
ABS CDO transactions. He thanked me and acted immediately to change policy
with the CDO group so that any new ABS CDO ratings would take into account
the pending downgrades of RMBS. A few weeks later Eric was transferred out of
the rating agency, Moody‟s Investors Service, to a different subsidiary. I was
disturbed by this sequence of events but never knew the whole story behind it.
Another disturbing incident from this period concerned a management meeting in
October or November of 2007. Moody‟s reputation had suffered a strong blow
with massive RMBS and related CDO and SIV downgrades. All the MDs
worldwide were invited to hear the CFO and CEO speak about the state of the
company. As was their practice, management opened the meeting with a lengthy
discussion about our profit margin relative to S&P and how this was viewed by the
equity analysts who rated our shares. Eventually, an MD from the corporate side of
the company raised his hand and asked what management was doing to restore our
lost reputation. The question seemed to take the CEO by surprise. I believe this
was the question on everyone‟s mind and most people in the audience were
disappointed that it was not the main topic of the meeting.
By the first half of 2008, Moody‟s reputation and employee morale was sinking. I
had been speaking with some faculty from Temple since December 2007 as I
prepared to exit Moody‟s. I resigned and left on good terms at the end of June
2008. I taught a training course for Moody‟s on structured finance on a consulting
basis in the fall of 2008 but was never constrained by any financial arrangement in
my ability to offer honest opinions.
22

Summary Remarks
In my opening remarks I go to some length to correct the misperception that rating
agencies were the primary cause of the financial crisis but it is certainly true that
excess trust in ratings badly burned many investors. Worse from a perception
standpoint is the fact that rating agencies completely missed the significance of the
housing boom but perversely were well-compensated as a result.
As the dust settles, I see two clear goals on the horizon. De-emphasize the role of
ratings in regulatory risk assessment and create a balance in the incentives for
rating agencies to address the conflict of interest embedded in their business
model. Again my ideas on this subject are in the piece I submitted entitled
“Reforming Credit Rating Agencies.”
Finally, we are today engaged in an effort to understand the lessons of the recent
financial crisis to build a stronger financial system and stronger economy. When
considering the role of the rating agencies, we should not lose sight of the obvious.
Mindless bashing of rating agencies can lead in the worst case to a defensive
reaction on their part, keeping ratings lower than they should be. At a time of
diminished confidence in financial markets, it is all the more important that rating
agencies aim for the right rating, not the lowest rating. Interest rates on corporate,
consumer and government debt are influenced by ratings. We will all pay a price if
rating agencies are beaten down into a defensive posture.

Rebuttal to Elliot Blair Smith’s Bloomberg Article of Sep 25, 2008
Motivation: I include this section because the FCIC staff and other governmental
investigators and numerous reporters who have contacted me since its
publication have used this misleading article as a primary source for information
about Moody’s rating practices and my role in them. This article was recently
referenced in a popular book, 13 Bankers, by Simon Johnson.
On Sep 25, 2008, Elliot Blair Smith (EBS) published a sensational, misleading and
internally inconsistent article on Bloomberg’s website entitled “Race to Bottom at
Moody's, S&P Secured Subprime's Boom, Bust.” Smith strings together innuendo
and cherry-picked quotes as “evidence” of Moody’s participation in this race. The
23

article centers on a paper I published on Moody’s website on August 10, 2004
entitled” Moody’s Correlated Binomial Default Distribution.” For reasons that I do
not understand, I was the highlight of all his evidence against Moody’s. Both
published Moody’s papers EBS mentions were written by me. No then current
Moody’s employees outside the PR department were mentioned. I spoke with
one of the other two former Moody’s employees quoted in the article. He shared
my frustration at being quoted out of context to support conjectures with which
he disagreed. I wrote to EBS with a complaint shortly after the story was posted.
He never responded.
EBS Claim: My Aug 10, 2004 paper on the Correlated Binomial “allowed securities
firms to sell more top-rated, subprime mortgage-backed bonds than ever before”
initiating a “Race to the Bottom” between S&P and Moody’s.
That was the first paragraph. In the second paragraph, he claims S&P began
making changes the next week.
Assuming no one will notice, he switches from the topic from sub-prime
residential mortgages in paragraph one to commercial real estate assets in
paragraph two with no explanation how or why they are related. EBS wrote, ‘A
week later, S&P moved to revise its own methods. An S&P executive urged
colleagues to adjust rating requirements for securities backed by commercial
properties because of the ``threat of losing deals.''’
My Response: My Aug 04 paper was never adopted by Moody’s to rate ABS CDOs.
Had it been adopted, it would have raised Moody’s standards.
The methodology from my Aug 04 paper was approved only for TRUPs and
ABS CDOs with a diversity score less than ten (see footnote 4). In practice,
ABS CDOs were not rated using the methodology from this Aug 04 paper.
Bond indentures from CDOs of this time period will clearly show that the
diversity scores were above ten and the older BET (Binomial Expansion
Technique) model was still in use for at least ten more months.
Had the Aug 04 methodology been used for ABS CDOs during 2004-2005
with diversity scores between 12 and 16, it would have increased the
24

projected expected loss for Moody’s Aaa CDOs relative to the older BET
methodology. This would have resulted in Aaa CDOs with additional
subordination to cushion them from loss. On page 8, Table 4, the paper
clearly demonstrates this for CDOs with diversity scores of 8 and 10. Results
are similar for diversity scores 12-16. There is no evidence offered in this
piece that my paper did or would have lowered Moody’s standards.
Although EBS is careful to avoid saying it explicitly, the quote from S&P is
placed to strongly imply that S&P reacted to my paper by making changes
to rating requirements for securities backed by commercial properties. My
paper made no reference to CMBS or commercial deals of any kind. There
was no reason for this S&P executive, named later in the article as Gale
Scott, to be concerned that my paper would even be used for CMBS related
transactions. I seriously doubt that Gale Scott had my paper in mind or was
even aware of my paper or me when making changes to rating
requirements for securities backed by commercial properties. EBS was no
doubt aware that it is almost certainly pure coincidence that the referenced
S&P emails were sent one week after my paper was published on Moody’s
website.
EBS Claim: My Aug 04 paper “dispensed with the diversity test”.
My Response: The Correlated Binomial as described in the Aug 04 paper retained
the diversity score as a critical input to the rating model.
The whole purpose of the Correlated Binomial was to retain the diversity
score while introducing correlation explicitly into the model. The diversity
score is retained as a key input for the Correlated Binomial rating
methodology in Expression 4 on page 5 for all CDOs where the diversity
score is known (as in ABS CDOs).
The older BET model assumed that assets were independent (i.e. zero
correlation). As ABS CDOs became more concentrated in RMBS after 2003,
the average correlation among the assets increased. My biggest fear at the
time I was promoted to MD in the CDO group (Mar 2004) was that our BET
model accounted for correlation in an ad hoc way that could not reflect the
25

increasing correlation among the assets of the CDOs we were rating. I
developed the Correlated Binomial to allow Moody’s to retain a model with
the simplicity, ease of use and intuitive appeal of the BET and to retain its
popular diversity score parameter calculated from default correlations. This
Aug 04 paper was intended to present an alternative to using normal
copula simulations that S&P, Fitch and all the I-banks adopted. I was
overruled and Moody’s adopted a Normal Copula approach in June 2005.

Sep 2005 Paper: Just before leaving the CDO group in September 2005, I wrote an
algorithm to determine a normal copula asset correlation (Moody’s Asset
Correlation or just MAC) that when be converted to a default correlation could be
used in the correlated binomial to replicate the loss distribution from the normal
copula as specified in the June 2005 paper mentioned in the above bullet point.
Cash ABS CDOs were rated using this scheme after I left the CDO group. The idea
was that the MAC would be a single measure of portfolio concentration similar to
the diversity score. Also, the correlated binomial was a closed-form distribution
with only three parameters and so was much easier to use than a normal copula
simulation. So after September 2005, Moody’s did use the correlated binomial to
rate ABS CDOs as a computational convenience but only in a way that guaranteed
that the expected loss and hence the rating would replicate the normal copula.
EBS references the September 2005 paper writing “In September 2005, Witt and
colleagues published a follow-up analysis. Compared with the BET, the new model
now projected that the likelihood of collateral defaults affecting CDO bonds rated
at least Aa could be 73 percent lower at the extreme, in a range of possibilities.” I
have no idea what he means here. The Sep 05 paper makes no projections of
collateral default or expected loss based the BET.
EBS Claim: In the section entitled “Tale of Two CDOs”, EBS compares Belle Haven
in Dec 2004 to McKinely Funding III in Dec 2006. EBS points out that the leverage
on the later deal was higher and writes, “Both CDOs were downgraded as the
subprime market deteriorated, with the earlier CDO holding up better than the
later one.”
26

My Response: All CDOs backed by RMBS have performed very poorly as the US
has sustained the largest nationwide decline in house prices in its history. This is
not the result of lower rating standards at Moody’s.
The deal issued later in Dec 2006 contains collateral backed by houses sold
later and so presumably at a higher price. These mortgages are further
underwater. It is no surprise that the later CDO has a worse performance.
I do not have the deal documents from the two transactions but have
anecdotal evidence that the average rating on the later deal was much
higher. (This would be reflected in Moody’s Weighted Average Rating
Factor or WARF, Moody’s most important measure of credit risk of the
underlying securities of a CDO.) This would probably account for much of
the difference in the subordination between the two transactions but he
does not report the WARF so I cannot say.
This is however, the one piece of his story concerning Moody’s that may
contain a grain of truth. My biggest concern with the normal copula was
that it could lower standards for high-grade ABS CDOs (WARF under 100 or
an average rating of underlying collateral of single A or higher), of which
these two are examples. However these were a minority of ABS CDOs. The
larger share of ABS CDOs were mezzanine deals. These were the CDOs that
had the worst performance. For mezzanine ABS CDOs concentrated heavily
in RMBS, I do not believe that Moody’s changes in methodology lowered
standards. Further, it is ironic that this article mentions only me as an active
decision maker at Moody’s during this time period when I offered an
alternative to the normal copula and was overruled. It was the use of the
normal copula that may have resulted in a lowering of Moody’s standards
for this minority of RMBS CDOs. I qualify this statement with “may”
because other modeling changes were made in June 2005 that may have
mitigated the impact of the normal copula for high-grade ABS CDOs.

Summary: I left the CDO group at Moody’s in September 2005 (a fact that EBS
knew but never states). As far as I know, the only substantial change to the
27

Moody’s modeling methodology for ABS CDOs between September 2000 and
September 2007 was the change from the two-moment BET and its default
correlation assumptions to CDOROM with its asset correlations in June 2005. This
article by EBS claims Moody’s participated in a race to the bottom in its subprime
ABS CDO modeling methodology and so makes the implicit assumption that
Moody’s BET approach was superior to Moody’s later correlation-based modeling
method for ABS CDOs for modeling the highly correlated subprime RMBS. I
disagree with this assumption in general and in particular disagree with the
notion that the large volume of subprime CDOs would not have been issued had
Moody’s continued to use the BET for rating ABS CDOs.
Aaa rated ABS CDOS spreads to Libor were above 60 in 2003 and fell steadily
to below 30 by June of 2005. They did not rise above 40 until March 2007.
Moody’s methodology was completely transparent which is why EBS was able
to read all about it. Why did investors continue to demand these assets at
increasing lower spreads if rating standards were declining as EBS states?
I believe the simple truth is that Moody’s, along with virtually the entire capital
market, failed to grasp the magnitude or significance of the housing bubble
until 2007 and assumed that no large-scale nationwide declines in house prices
would occur because they had not occurred since the Great Depression which
people viewed as a singular, remote time period that would not be repeated.
Moody’s models for both RMBS and CDOs were based on fairly recent
historical data and so implicitly assumed that large scale house price declines
would not happen. Earlier model versions made the same assumption. My
best understanding is that there was no systematic decline in the standards of
Moody’s ABS CDO models. There was a systematic decline in the credit quality
of the underlying mortgage loans that Moody’s models, along with almost
everyone else’s models, failed to address.

28