Default Probability and Loss Given Default
for Home Equity Loans
Michael LaCour-Little
Yanan Zhang
Office of the Comptroller of the Currency
Economics Working Paper 2014-1
June 2014
Keywords: mortgage default, loss given default, home equity loans, securitization.
JEL classifications: G21, G28.
Michael LaCour-Little is a professor of finance at California State University at Fullerton (e-mail
mlacour-little@fullerton.edu). Yanan Zhang is a financial economist at the Office of the
Comptroller of the Currency (e-mail yanan.zhang@occ.treas.gov), 400 7th St. SW, Washington,
DC 20219, telephone (202) 649-5465; fax (571) 465-3935.
The views expressed in this paper are those of the authors alone and do not necessarily reflect
those of the Office of the Comptroller of the Currency or the U.S. Department of the Treasury.
The authors would like to thank Michele Tezduyar for editorial assistance.
The authors take
responsibility for any errors.
. Default Probability and Loss Given Default
for Home Equity Loans
Michael LaCour-Little
Yanan Zhang
June 2014
Abstract: Securitization has been widely assigned blame for contributing to the recent mortgage
market meltdown and ensuing financial crisis. In this paper, we sample from the OCC Mortgage
Metrics database to develop estimates of default probabilities and loss given default for home
equity loans originated during 2004-2008 and tracked from 2008-2012. We are particularly
interested in the relationship between loan outcomes and the lender’s decision to securitize the
asset. Among other innovations, we are able to measure the change in the borrower’s credit score
over time and the level of documentation used during loan underwriting.
Results suggest that
securitized home equity loans bear higher default risk and produce greater loss severity than
loans held in portfolio by lenders.
Economics Working Paper 2014-1
i
. 1. Introduction
Securitization, particularly non-agency securitization of subprime and Alt-A mortgages, has been
identified as a contributory factor in the recent financial crisis (see, for example, Keys,
Mukherjee, Seru, and Vig [2010] or Keys, Seru, and Vig [2012]). While first mortgage loans
have been widely studied, home equity loans have not. The current paper addresses this gap in
the literature utilizing the Office of the Comptroller of the Currency (OCC) Mortgage Metrics
dataset.
To preview our main result, we find that securitized home equity loans do have greater
default probability (PD) and loss given default (LGD) than loans retained in portfolio by major
banks.
While less frequently studied than first mortgages, home equity loans grew rapidly during the
period 2000-2008 and became a sizable segment of the mortgage market. The total dollars
outstanding of home equity loans increased from $275.5 billion in 2000 to a peak of $953.5
billion in 2008, an average annual growth rate of 16.8 percent. Likewise, the total number of
home equity loans increased from 12.9 million in 2000 to a peak of 23.8 million in 2007, an
average annual growth rate of 9.1 percent.
Since balances were growing faster than accounts,
average loan size was increasing over the period as well. Unlike first lien loans, the majority of
which are securitized, most home equity loans remain on bank balance sheets. Aggregate bank
risk exposure to home equity loans is estimated to be 30 percent of the total residential mortgage
exposure, or roughly $750 billion (Fitch Ratings, 2012).
As the private-label mortgage
securitization market has recently shown signs of resurgence, home equity loans are again
evident (Inside Mortgage Finance, 2013).
Research has also shown that junior lien lending through home equity loans is related to the
documented increase in household leverage (Mian and Sufi [2011]) and to the much-reported
decline in personal savings (Greenspan and Kennedy [2008]). Moreover, increased debt usage
through home equity lending can also dilute equity in a borrower’s home, thereby increasing the
default risk of first mortgages and magnifying the impact of declining house prices on default
and foreclosure rates (LaCour-Little [2004]). Likewise, LaCour-Little, Sun, and Yu (2013) find
Economics Working Paper 2014-1
1
.
that greater home equity lending at the zip code level, especially of home equity lines of credit
(HELOC), is related to higher rates of mortgage default on first mortgages in the same area.
Our contribution in this paper is to examine the PD and loss severity of home equity loans during
the recent market downturn, 2008-2012. Among other enhancements, we have a measure of
borrower credit score over time, allowing us a rough proxy for changes in the borrower’s
financial position prior to default. Moreover, we have measures of income and asset verification,
so that we can quantify the role of reduced documentation in default risk.
The paper is organized as follows. In the next section, we review the literature on mortgage loan
performance, and the more limited research on LGD generally and home equity lending in
particular.
In the third section, we describe our data and sampling approach. In Section IV, we
present regression models of PD and discuss results. Section V presents the data used and
regression models estimated for LGD estimates, including a discussion of results.
Section VI
presents conclusions and extensions in progress.
2. Literature Review
PD and LGD on fixed income instruments are a longstanding topic of interest in finance. For
example, Altman, Resti, and Sironi (2003) present a broad review of the literature and the
empirical evidence of default recovery rates in credit-risk modeling.
Their paper focuses on the
relationship between PD and LGD and how this relationship is treated in different modeling
frameworks. Recent empirical evidence cited suggests that LGD is positively correlated with
PD. 1
The evolving Basel standards have stimulated additional research on LGD.
Schuermann (2004),
for example, analyzes the definition and measurement of LGD in the context of Basel II and
analyzes data from Moody’s Default Risk Service Database. Among his findings, he reports that
1
See details of the empirical evidence in Frye (2000a, b), Jarrow (2001), Carey and Gordy (2003), and Altman et al.
(2001, 2004).
Economics Working Paper 2014-1
2
. the recovery distribution is bimodal, lower in recessions than in expansions. Both the Altman and
Schuermann papers are based on corporate bond data.
Relatively fewer papers focus on consumer loans, such as credit card or home mortgage debt,
although this literature is growing rapidly. This is probably due to the absence of publicly
available data, since most of these loans reside on bank balance sheets, and lender focus on PD
modeling. An early paper that is focused on LGD for residential mortgages is Lekkas et al.
(1993).
They test the frictionless options-based mortgage default theory empirically and report
that higher loss severity is associated with higher original loan-to-value (LTV), geographical
locations with higher default rates, and younger mortgage loans. Crawford and Rosenblatt (1995)
incorporate transaction costs into the options-based mortgage default model and empirically test
its effect on loss severity. Among their findings is that LGD is reduced where the probability of a
deficiency judgment is higher.
Among more recent papers focused on mortgage loans, Calem
and LaCour-Little (2004) also analyze the determinants of LGD. Their regression results confirm
Lekkas et al. (1993) for either original LTV or combined loan-to-value (CLTV).
They also report
that both mortgage age and loan size have significant effects on LGD, with smaller loans
exhibiting higher loss severity due to fixed costs associated with exercising the foreclosure
option.
More recently, Qi and Yang (2009) study LGD of high LTV loans using data from private
mortgage insurance companies. They find that CLTV is the single most important determinant of
LGD. They find that mortgage loss severity in distressed housing markets is significantly higher
than under normal housing market conditions.
In a study unrelated to mortgage lending, Bellotti
and Crook (2009) study LGD models for UK retail credit cards. They compare several
econometric methods for modeling LGD and find that Ordinary Least Squares models with
macroeconomic variables perform best to forecast LGD at both the account level and the
portfolio level. The inclusion of macroeconomic variables enables them to model LGD in
downturn conditions as required by Basel II.
Most of these studies have focused on testing particular theories and underlying relationships.
Studies on business cycle effects remain limited, although there have been some attempts to test
Economics Working Paper 2014-1
3
.
the downturn effect. For example, Calem and LaCour-Little (2004) examine the relationship
between LGD and the economic environment using simulation at the portfolio level. Qi and
Yang (2009), cited above, test the effect of housing market downturns by inclusion of a dummy
variable.
For home equity lending specifically, the literature is much more limited. Canner, Fergus, and
Luckett (1988) describe the early stages and growth of the home equity lending segment,
following passage of the 1986 tax law changes which are generally acknowledged to have
accelerated the growth of this segment of consumer lending.
2 Weicher (1997) reviews the home
equity lending industry during the 1990s, characterizing it as business based on recapitalizing
borrowers with impaired credit but substantial housing equity. LaCour-Little, Calhoun, and Yu
(2011) focus on simultaneous close or “piggyback” loans, and find that such lending is
associated with higher default and foreclosure rates in subsequent years. Goodman, Ashworth,
Landy, and Yin (2010) report that the presence of junior lien mortgages increases the default risk
of first lien mortgages.
Ambrose, Agrawal, and Liu (2005) show that patterns of home equity
line use are also related to borrower credit quality, as measured by their FICO scores. Extending
that analysis further, Agarwal, Ambrose, Chomsisengphet, and Liu (2006) examine the
performance of home equity lines and loans, finding considerable difference in terms of default
and prepayment risk. Agarwal, Ambrose, Chomsisengphet, and Liu (2010) examine the role of
soft information in home equity lending and find that its use can be effective in reducing default
risk.
LaCour-Little, Rosenblatt, and Yao (2010) document the magnitude of equity extraction by
homeowners during the period 2000-2006. Cooper (2010) finds that high equity extraction has
been used both for household expenditures and home improvement during the 2000-2006
housing boom.
The present paper contributes to the existing literature on LGD and home equity lending in the
following ways. First, we sample from a comprehensive dataset of mortgage lending by the
largest commercial banks in the U.S.
Second, due to the richness of this dataset, we are able to
employ a reasonable proxy for the financial positions of households utilizing their current credit
2
Prior to 1986, most interest on consumer debt was tax-deductible; after the 1986 tax law changes, only residential
mortgage debt remained generally deductible for those who itemize deductions.
Economics Working Paper 2014-1
4
. scores. Third, we have measures for the level of documentation used in loan underwriting,
allowing us to quantify the effect of “low doc” underwriting on default risk. Finally, since we
have information on whether the loan was securitized or not, we are able to examine the
correlates of that decision on subsequent loan performance.
3. Data and Sampling Scheme
The data used in this research is a sample taken from the OCC’s Mortgage Metrics database.
This is a loan-level dataset of monthly servicing information from nine large national banks
assembled by LPS Applied Analytics and provided to the OCC.
The database is quite rich and
contains more than 80 fields. Variables denote the borrower’s credit profile, loan product details,
collateral information, and loan performance history, including both delinquency and loan
modification information. Collection of monthly performance information began in May 2008
and continues to the present; accordingly, we will be able to update results as more time passes.
The underlying loans account for two-thirds of the overall home equity market, and there are
more than 9 million loan records added to the database each month.
This is truly “big data.”
In table 1A, we present a snapshot of the database as of December 2009 to better illustrate the
distribution of loans in the database. There are 10.5 million loans in active status at the end of
2009; of these, 8.2 million are in second lien position; of these, 7.2 million were originated
between 2004 and 2008 and are either held in portfolio or securitized by private issuers. Of the
7.2 million second liens, 2.0 million, or about 28 percent, are home equity loans (sometimes
called closed end seconds or CES), and the rest are HELOCs.
Economics Working Paper 2014-1
5
.
LOAN_OWNER
All
LoanCount
Avg
Balance
INTRATE_ INTRATE_C CLTV_ CLTV_C FICO_O FICO_C
ORIG
URR
ORIG URR
RIG
URR
DTI
arm
Income
Asset
Document Document
ed
ed
subprime
All
7,215,037
$56,001
7.29%
5.14%
78.6
74.7
735
717
36.6
73.5%
6.6%
25.3%
11.8%
Securitized
542,302
$46,579
7.20%
7.54%
86.2
97.9
715
685
35.7
66.6%
3.0%
39.0%
3.5%
Portfolio
6,672,735
$56,762
7.30%
4.94%
78.0
72.8
736
720
36.6
74.1%
6.9%
24.2%
12.5%
HE Loan
All
2,005,284
$48,522
8.17%
8.00%
84.3
86.9
724
702
36.6
5.7%
14.6%
40.7%
17.3%
%Sec'tzd
Securitized
182,282
$43,077
8.42%
8.60%
89.2
88.3
713
678
37.3
0.5%
7.8%
48.8%
7.8%
Portfolio
1,823,002
$49,057
8.15%
7.94%
83.9
86.7
725
704
36.5
6.2%
15.2%
39.9%
18.3%
%Sec'tzd
7.5%
9.1%
HELOC
%Sec'tzd
6.9%
All
5,209,753
$58,870
6.91%
4.03%
76.5
70.6
739
723
36.5
99.7%
3.6%
19.4%
9.7%
Securitized
360,020
$48,319
6.62%
7.01%
84.8
102.4
716
689
35.0 100.0%
0.6%
34.0%
1.3%
Portfolio
4,849,733
$59,653
6.93%
3.81%
75.8
68.1
741
726
36.7
3.8%
18.3%
10.3%
99.6%
The share of securitized loans overall is 7.5 percent. The next table shows how securitization
patterns and average loan characteristics have evolved over time.
LoanCount
AvgBal
INTRATE_ INTRATE_ CLTV_ CLTV_C FICO_ FICO_C
CURR
ORIG
ORIG URR ORIG URR
origyr
securitized
DTI
arm
subprime
Doc_i
Doc_a
2003
No
533,121
$39,113
5.10%
4.29%
75
51
739
744
32
83%
4%
20%
14%
2003
Yes
42,896
$24,719
4.35%
5.34%
82
72
725
716
32
89%
1%
45%
1%
2004
No
812,061
$47,084
5.40%
4.26%
77
60
737
733
35
86%
6%
22%
15%
2004
Yes
71,001
$35,997
4.83%
6.02%
85
93
719
698
35
94%
5%
46%
9%
2005
No
1,323,251
$55,931
6.87%
4.64%
79
72
735
723
36
78%
9%
24%
14%
2005
Yes
107,594
$45,482
6.38%
7.54%
86
106
715
680
35
91%
8%
43%
8%
2006
No
1,628,302
$61,651
8.20%
5.27%
79
77
733
709
38
68%
10%
21%
11%
2006
Yes
208,498
$52,215
8.27%
8.17%
87
96
711
676
37
52%
2%
35%
2%
2007
No
1,793,137
$61,202
8.38%
5.53%
80
82
733
707
38
65%
6%
24%
10%
2007
Yes
112,300
$52,299
8.48%
8.20%
88
107
716
689
36
44%
0%
35%
0%
2008
No
582,863
$60,971
6.12%
4.43%
72
70
753
742
36
84%
2%
42%
16%
2008
Yes
13 $448,810
3.17%
6.80%
21
49
733
642
42
31%
46%
100%
100%
Sampling from the Database
In this section we briefly describe the construction of the dataset we use for this research. We
include data cleaning and the creation of the panel dataset itself.
Data Cleaning
Whenever large datasets are involved, data cleaning is necessary. Upon sanity checking of the
dataset, we noticed data anomalies and outliers that are better left out of the regression analysis.
Since we are dealing with a large dataset, it is safe to leave out observations that are below 1
Economics Working Paper 2014-1
6
.
percentile or beyond 99 percentile. For HELOAN and HELOC portfolios respectively, these are
the p1 and p99 values for key numeric variables used in the regression analysis.
HELOAN
cltv_curr
cltv_orig
DTI
intrate_curr
intrate_orig
loanamt
p1
2
15
7
0.041
0.056
7
p99
195
100
60
0.126
0.126
60
HELOC
cltv_curr
cltv_orig
DTI
intrate_curr
intrate_orig
loanamt
p1
2
30
7
0.023
0.036
7
p99
195
100
70
0.13
0.13
70
Our data cleaning rules are largely based on the above table, and in some instances we relaxed
the p1 or p99 constraint and selected a value smaller than the p1 value or greater than the p99
value if these values did not seem to be extreme values. For example, instead of using the p1
value of 0.041 for the lower bound of current interest rate, we only require this lower bound to be
greater than zero, since lower interest rates may well be teaser rates and are not data anomalies.
We have learned that teaser rates are small but never are zero, so we require a valid interest rate
to be greater than zero. The upper bound for interest rates we chose is 0.13, consistent with the
p99 value.
For current LTV, we require it to be between 2 and 195, as the p1 and p99 values
suggest. For original LTV, we selected values between 1 and 100, where 100 is the p99 value,
while 1 is closer to the minimum value. For debt-to-income ratio (DTI), we chose values
between 7 and 100, as 7 is the p1 value and 100 is closer to the maximum value.
For loan
amounts, we chose values that are larger than 7,000, the p1 value, while selecting everything up
to the maximum value, which we assess to be reasonable.
Creating the Balanced Panel for Modeling
Panel data for securitized loans consist of 11.1 million loan months derived from 0.51 million
unique loans. Since portfolio loans are more than 10 times the number securitized, we selected a
random sample of portfolio loans of 0.51 million—the exact same number of loans as the
securitized loans. The panel data of these portfolio loans consist of 10.7 million loan months.
We
then pooled the securitized and held-in-portfolio loan months together, resulting in panel data of
22 million loan months. Of these, defaults occur in 207,000 loan months. In other words, we
observe a loan default in slightly less than 1 percent of all loan months in the panel data sample,
Economics Working Paper 2014-1
7
.
as defaults are over-weighted. In terms of gross lifetime default rate, this is about a 3 percent
default rate based on the 7.2 million total loan count shown in table 1A. We kept all these loan
months in our final estimation dataset and randomly selected the same number of loan months
from the non-defaulted loan months. The result of this procedure is a final sample consisting of
414,000 loan months.
At each point in time, we characterize loans in terms of their status, which initially takes on one
of three values: currently active, defaulted, or paid off.
Default and paid off are the terminal
states that we will model. There are additional subtleties to be considered; e.g., properties sold by
their owners as short sales generally impose losses on lenders, yet those loans may not have
actually defaulted prior to the short sale. Are such events defaults or prepayments? We will have
to sort out such issues prior to the next version of this paper.
4.
Regression Analysis–Default Probability
Our general approach is to estimate a multinomial logit for our probability of default model and
employ OLS to estimate LGD for those loans that have defaulted. As these methods are widely
used in the literature, we do not present details here, but will include a more complete discussion
of methodological choice in the next version of this paper.
We estimated default and prepayment for HELOAN and HELOC separately, controlling for loan
age, current combined LTV (CCLTV), original FICO, change in FICO since origination
(FICO_DRIFT), DTI, whether underwriting included income and asset verification or not
(DOC_I and DOC_A), whether the loan was subprime or not, and whether the loan is securitized
or not. We treat HELOAN and HELOC as two distinct loan segments, since HELOAN behaves
more like traditional mortgages, while HELOC has the initial draw period until the loan limit is
reached and is then followed by an amortization period, so sensitivities and timing of default and
prepayment may well be very different between these two product groups.
Results appear in
tables 3A and 3B on the next page. Table 3A provides coefficients and standard errors. Table 3B
provides odds ratios, the typical method for evaluating the effect of indicator variables on the
loan status dependent variable when using a logit model.
We discuss results following the tables.
Economics Working Paper 2014-1
8
. Table 3A:
Default Logit for HELOAN and HELOC
HELOAN
HELOC
Parameter
Intercept
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
Intercept
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
Estimate
8.2375
-0.0246
0.000675
-0.0122
-0.0195
0.6146
0.00376
-0.1077
-0.2787
0.6794
9.3857
-0.018
0.00281
-0.0148
-0.021
0.6715
-0.00757
-0.1355
-0.0876
0.618
Std Error
0.1292
0.000562
0.000151
0.000164
0.000105
0.0173
0.000739
0.0165
0.0343
0.0269
0.0952
0.000357
0.000115
0.000123
0.000078
0.0133
0.000502
0.0137
0.0321
0.0354
Wald Chi-sq
4066.5
1921.0
20.1
5556.3
34470.1
1261.3
25.8
42.4
66.1
638.2
9717.1
2523.9
592.7
14475.6
72540.7
2540.3
226.7
97.2
7.5
303.9
Prob
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
<.0001
0.0063
<.0001
Std Error
0.9679
0.00369
0.00107
0.0012
0.000911
0.1216
0.00497
0.1168
0.199
0.209
0.7794
0.00251
0.000968
0.000951
0.00075
0.0986
0.00385
0.0953
0.1746
0.3135
Wald Chi-sq
89.5
16.1
20.4
19.4
40.0
6.6
1.0
0.5
13.9
6.5
229.0
66.6
6.5
55.6
63.7
22.8
7.6
7.8
6.3
0.6
Prob
<.0001
<.0001
<.0001
<.0001
<.0001
0.0101
0.3278
0.477
0.0002
0.0111
<.0001
<.0001
0.0106
<.0001
<.0001
<.0001
0.0057
0.0052
0.0118
0.4222
Prepayment Logit for HELOAN and HELOC
HELOAN
HELOC
Parameter
Intercept
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
Intercept
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
Economics Working Paper 2014-1
Estimate
-9.1578
0.0148
-0.00485
0.00528
0.00576
0.313
-0.00486
-0.083
0.741
-0.5309
-11.7951
0.0205
-0.00247
0.00709
0.00598
0.471
-0.0106
0.2662
0.4397
0.2516
9
. Table 3B:
HELOAN
HELOC
HELOAN
HELOC
Default Odds Ratio
Variable
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
Estimate
0.976
1.001
0.988
0.981
1.849
1.004
0.898
0.757
1.973
0.982
1.003
0.985
0.979
1.957
0.992
0.873
0.916
1.855
95% CL-Lower
0.975
1
0.988
0.98
1.787
1.002
0.869
0.708
1.871
0.982
1.003
0.985
0.979
1.907
0.991
0.85
0.86
1.731
95% CL-Upper
0.977
1.001
0.988
0.981
1.913
1.005
0.927
0.809
2.08
0.983
1.003
0.986
0.979
2.009
0.993
0.897
0.976
1.989
Prepayment Odds Ratio
Variable
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
age
CLTV_CURR
FICO_ORIG
fico_drift
securitized
DTI
Doc_i
Doc_a
subprime
Estimate
1.015
0.995
1.005
1.006
1.367
0.995
0.92
2.098
0.588
1.021
0.998
1.007
1.006
1.602
0.989
1.305
1.552
1.286
95% CL-Lower
1.008
0.993
1.003
1.004
1.077
0.986
0.732
1.42
0.39
1.016
0.996
1.005
1.005
1.32
0.982
1.083
1.102
0.696
95% CL-Upper
1.022
0.997
1.008
1.008
1.736
1.005
1.157
3.099
0.886
1.026
0.999
1.009
1.007
1.943
0.997
1.573
2.185
2.377
Economics Working Paper 2014-1
10
. Probability of Default Preliminary Results–Discussion
Signs and magnitudes of coefficients are generally consistent for both HELOAN and HELOC,
and are generally as expected, although the age variable has a negative sign, probably reflecting
the time period we study, during which house prices were declining so that newer originations
experienced greater overall house price depreciation than older loans. The only variable that has
different signs for HELOAN and HELOC is the DTI variable; it is positive for HELOAN, which
behaves more like traditional mortgages, and negative for HELOC, possibly indicating that
borrowers with greater need for liquidity are less likely to default on their lines of credit.
As expected, borrower FICO score is negative and highly statistically significant in the default
equation, but positive in the prepayment equation, confirming the often observed pattern that
better borrowers are less likely to default but more likely to prepay, and vice-versa. Current LTV
ratio is also highly statistically significant with expected signs. Borrowers with higher current
LTVs are more likely to default but less likely to prepay.
As mentioned earlier, we also have a measure of the borrower’s current credit score and calculate
its change from the point of origination (FICO_DRIFT).
A decline in credit score may be viewed
as a proxy for financial problems; an increase, for improvements in overall financial position.
This proves to be a highly predictive variable, as it is certainly the most statistically significant
variable in the default equations. Borrowers with declines in credit score are much more likely to
default and borrowers with improved credit score are much more likely to prepay.
Other variables not often available to researchers include method of loan underwriting; in
particular, whether income and/or assets were documented (DOC_I; DOC_A). Consistent with
an emerging literature (and common sense), verifying income and assets appears to reduce
default risk, with odds ratios of between 0.70 and 0.92, respectively.
Results are less clear in the
prepayment function, as both coefficients are positive, indicating greater prepayment risk, but the
coefficients are not all significant at the 5 percent level.
Economics Working Paper 2014-1
11
. As stated in the abstract, a key variable of interest is securitization. We find that securitized loans
have both higher default and prepayment risk than portfolio loans, with odds ratios of 1.9-2.0 and
1.4-1.6, respectively, which is even higher than the odds ratio for the “subprime” variable. We
will refine these estimates, adding control variables as necessary and tests for sample selection
bias.
5. Loss Given Default Estimation
Inspection of descriptive statistics suggests that LGD is higher for securitized loans.
In terms of a
raw difference, we note a 92 percent mean loss severity for securitized loans, compared with an
85 percent loss severity rate for portfolio loans. Our effort here is to determine whether this
difference persists after controlling for other factors that may affect loss severity. For the LGD
regressions, we did not separately estimate equations for HELOAN and HELOC loans, since we
believe that the behavioral patterns for LGD are sufficiently homogeneous between these two
groups.
Data
Our dataset is necessarily smaller, since we only have realized losses for loans that defaulted.
After excluding cases with important covariates missing, we have approximately 70,000
observations.
Lenders typically booked losses over several months following a 90-day
delinquency status (sometimes later). To arrive at the total loss amount, we summed these writedowns over time. Due to some data problems with missing values for current loan balance, we
define loss severity as the total loss amount as a fraction of initial loan amount.
In future
revisions, and as our problem with missing current loan balances is resolved, we will employ the
more traditional loss severity definition, namely the total loss amount as a fraction of balance at
time of default. In order to avoid large influential observations that could alter our regression
results, we performed data cleaning on the dataset to only use observations within the 1st
percentile and 99th percentile. For example, loans with original balances of less than $1,000 are
deleted, and severities less than -4 percent are eliminated.
After these cleaning procedures, we
still noticed that there are about 5 percent of loans with loss severity greater than 150 percent.
Economics Working Paper 2014-1
12
. For certain banks, there might be some problems with their loss reporting, so we will investigate
the data issue for the next round of analysis; for now, we removed these observations with
unreasonably large loss severities that are greater than 150 percent. Descriptive statistics are
shown in table below:
Variable
Mean
Severity
StdDEV
Minimum
Maximum
85
28
-4
150
LOAN_AMT
75,981
70,254
1,500
9,000,000
totloss
64,089
62,799
-15402
5,898,807
CLTV_ORIG
89
12
0.05
199
FICO_ORIG
710
46
365
899
-152
66
-469
250
fico_drift
Next, we compare mean severity for portfolio and securitized loans over time:
Loss Severity
Loss
Year
Portfolio
Securitized
2008
91
91
2009
89
95
2010
82
93
2011
84
88
2012
79
84
Overall
85
92
Economics Working Paper 2014-1
13
. Portfolio
origyr
All
#Loans
Severity
LOAN_AMT
Totloss
Comb_OLTV
FICO_ORIG
FICO_drift
634,688
85
$77,436
64,737
89
711
-151
2004
31,213
79
$64,756
50,121
88
704
-144
2005
111,416
85
$74,992
62,285
89
712
-149
2006
235,364
86
$78,833
66,867
89
712
-152
2007
235,901
84
$78,215
65,366
89
710
-152
2008
20,794
84
$84,916
68,574
84
717
-156
origyr
#Loans
Severity
LOAN_AMT
otloss
Comb_OLTV
ORIG
FICO_drift
All
74,074
92
$63,514
58,530
91
702
-158
2004
3,942
93
$51,592
47,461
92
703
-157
2005
13,576
94
$62,287
58,278
91
707
-160
2006
37,172
91
$64,937
59,368
90
700
-158
2007
19,362
92
$64,015
59,295
91
702
-155
2008
22
96
$111,125
107,181
79
731
-191
Securitized
In general, severity or LGD appears to be higher for securitized loans than portfolio loans and
higher for the 2005-2006 cohorts across both categories. We will control for these factors in our
regression models, discussed next.
Economics Working Paper 2014-1
14
. LGD Regression Models
Our initial LGD model (model A) incorporates loan age, loan size, LTV, product type (fixed or
adjustable rate mortgage [ARM]), credit class, HELOC or not, and a dummy variable for
securitization, our variable of interest. For the LTV variable, we initially used CCLTV, as we
suspect it will perform better than original combined (OCLTV). Unfortunately, a large share of
loans have missing values for combined CCLTV; moreover, since the standard deviation of this
variable is unusually large, especially when compared with OCLTV, we are concerned about the
accuracy and consistency of this variable across lenders. After preliminary tests, we found that
CCLTV actually performed worse than original OCLTV, which we employ in the regressions
reported below.
OCLTV has some virtues, of course, particularly since CCLTV cannot be used
for loan underwriting purposes, at least not without a necessarily uncertain forecast of future
house prices.
LGD Model A:
Beta
Std Err
T-Value
Prob
Intercept
74.146
0.303
244.9
<.0001
Age
-1.834
0.024
-77.4
<.0001
lnsize
-0.032
0.001
-43.0
<.0001
lnsize50
-0.126
0.004
-36.0
<.0001
lnsize300
0.027
0.002
17.1
<.0001
oltv
0.157
0.003
56.4
<.0001
-0.023
0.000
-46.9
<.0001
5.131
0.210
24.4
<.0001
-1.520
0.210
-7.2
<.0001
securitized
8.570
0.109
78.5
<.0001
subprime
7.023
0.085
83.0
<.0001
R-Square
3.9%
Variables
fico_drift
Arm
HELOC
This simple model produces very plausible results. Loss severity is decreasing in loan size and
increasing with LTV ratio. Two important predictors are credit class and securitization.
We
expect subprime loans to have much higher LGD than prime loans, so the strong positive
coefficient on subprime is as expected. However, securitization has an even greater impact.
Economics Working Paper 2014-1
15
. Adjustable rate instruments (ARM) have higher LGD, whereas HELOCs generate lower LGD.
This is consistent with the literature that HELOC loans are generally extended to higher income
and higher credit score borrowers. Lastly, the change in the borrower’s financial condition since
origination as captured by FICO_DRIFT is highly significant, as credit degradation increases
LGD.
Building on this baseline specification, we then added current note rate, a flag for loan
modification, and other controls, including state dummy variables (not reported below, in the
interest of table brevity) and loss-year dummies. Together, these latter two sets of dummy
variables should capture cross-sectional variation in housing market conditions and the statelevel legal environment, as well as the overall time trend in housing market conditions. The
current note rate proved to be a highly significant variable, since the higher the note rate, the
higher the lost interest accrual, adding to losses.
About 7 percent of loans are flagged as having
been modified through rate reduction, term change, or principal reduction. A dummy variable for
loan modification also proves highly significant, with an impact of -11 percent on the severity
rate.
While not reported, results of the state dummy variables are consistent with expectations. For
example, the so-called “sand states” of Arizona, California, Florida, and Nevada all have large
and statistically significant positive coefficients.
Likewise, states relatively less affected by the
market downturn and with more rapid foreclosure procedures, for example, Texas, have a large
and statistically significant negative coefficient.
Economics Working Paper 2014-1
16
. LGD Model B
Variables
Intercept
Beta
65.15
age
-0.79
lnsize
-0.03
lnsize50
-0.10
lnsize300
0.02
oltv
0.14
fico_drift
-0.02
arm
9.56
HELOC
-3.79
securitized
6.97
subprime
6.47
lossyr2009
0.34
lossyr2010
-4.96
lossyr2011
-1.56
lossyr2012
-3.17
INTRATE_CURR
80.29
mod
Std Err
-11.13
R-Square (adj) 0.064
T-Value
Prob
0.75
86.88
<.0001
0.037
-21.32
<.0001
0.001
-38.39
<.0001
0.004
-27.48
<.0001
0.002
14.7
<.0001
0.003
48.07
<.0001
0.001
-43.63
<.0001
0.221
43.18
<.0001
0.216
-17.54
<.0001
0.123
56.68
<.0001
0.087
74.72
<.0001
0.136
2.52
0.0116
0.146
-34.1
<.0001
0.17
-9.14
<.0001
0.209
-15.17
<.0001
1.767
45.43
<.0001
0.144
-77.42
<.0001
Model B is a much more refined specification than Model A. We note that adjusted R-squared
increased from 3.9 percent to 6.4 percent, which in our experience is relatively high for this type
of LGD model due to the intrinsic difficulties in modeling severity rate. Signs of coefficients are
also highly consistent across the two models. Securitization appears to add 7-9 percent to loss
severity.
This is approximately the same as the 7 percent raw difference in mean severity
mentioned at the beginning of this section and certainly quite economically significant.
Economics Working Paper 2014-1
17
. 6. Conclusion and Extensions
In this paper, we have sampled from a very large database of home equity mortgage loans made
by the largest commercial banks in the U.S. We examined loan performance, including LGD for
home equity loans, whether securitized or held in portfolio by the originator. We find an increase
in the probability of default among those loans that were securitized, and higher loss severity
among such loans as well.
We have additional work to do.
While initial results for the probability of default model are
encouraging, we need to incorporate interaction variables and otherwise test the specification to
ensure robustness of results. More importantly, we have not yet addressed potential sample
selectivity issues. If securitized home equity loans are systematically different than loans held in
portfolio, our initial modeling approach may be inappropriate.
Hence, we need to model the
lender’s securitization decision. We plan to rely on the established literature (Ambrose, LaCourLittle, and Sanders [2005] and Agrawal, Chang, and Yavas [2012]) to do so. Essentially, this
method is to develop models that lenders could have used at time of origination (hence, without
updated collateral values or changes to credit scores) to estimate default and prepayment, and
compare predicted probabilities with loan pricing; i.e., to assume lenders rationally retain loans
that have better risk and return profiles.
A final issue of possible sample selectivity relates to the
OCC Mortgage Metrics database itself. Since that database begins tracking loans only in 2008, it
is subject to potential survivorship bias if loans that terminated prior to 2008 are systematically
different from those whose performance we examine. Survivorship issues are a common
problem in the mortgage loan performance literature and we anticipate using standard methods to
test and/or correct our results.
Economics Working Paper 2014-1
18
.
References
Agarwal, Sumit, Yan Chang, and Abdullah Yavas. 2012. “Adverse Selection in Mortgage
Securitization.” Journal of Financial Economics 105(3): 640-660.
Agarwal, Sumit, Brent Ambrose, S. Chomsisengphet, and C.
Liu. 2006. “An Empirical Analysis
of Home Equity Loan and Line Performance.” Journal of Financial Intermediation 15: 444-469.
Agarwal, Sumit, Brent Ambrose, S.
Chomsisengphet, and C. Liu. 2005.
“Credit Lines and Credit
Utilization.” Journal of Money, Credit and Banking 38(1): 1-22.
Agarwal, Sumit, Brent Ambrose, Chomsisengphet, S., and Liu, C. 2011. “The Role of Soft
Information in a Dynamic Contract Setting: Evidence from the Home Equity Credit Market.”
Journal of Money, Credit and Banking 43(4): 633-655.
Altman, Edward I.
2001.“Altman High Yield Bond and Default Study,” Salomon
Smith Barney, U.S. Fixed Income High Yield Report, July.
Altman, E. and G.
Fanjul. 2004. “Defaults and Returns in the High Yield Bond Market:
Analysis Through 2003,” NYU Salomon Center Working Paper, January (also
through 2003 Q3).
Altman, Edward, Andrea Resti, and Andrea Sironi.
2003. “Default Recovery Rates In Credit
Risk Modeling: A Review of the Literature and Empirical Evidence,” Working Paper, New York
University.
Ambrose, Brent W., and Michael LaCour-Little. 2005.
“A Note on Hybrid Mortgages.” Real
Estate Economics 33(4): 265-290.
Ambrose, Brent W., Michael LaCour-Little, and Anthony Sanders. 2005. “The Effect of
Conforming Loan Status on Mortgage Yield Spreads: A Loan Level Analysis,” Real Estate
Economics 32: 541-569.
Bellotti, Tony and Jonathan Crook.
2009. “Loss Given Default Models for UK Retail Credit
Cards,” Working Paper, Credit Research Centre, University of Edinburgh Business School.
Calem, Paul S. and Michael LaCour-Little.
2004. “Risk Based Capital Requirements for
Mortgage Loans.” Journal of Banking & Finance 28: 647-672.
Canner, G.B., J.T. Fergus, and C.A.
Luckett. 1988. “Home Equity Lines of Credit.” Federal
Reserve Bulletin, June, 361-373.
Carey, Mark and Michael Gordy.
2003. “Systematic Risk in Recoveries on Defaulted
Debt,” mimeo, Federal Reserve Board, Washington.
Economics Working Paper 2014-1
19
. Cooper, D. 2010. “Did Easy Credit Lead to Overspending? Home Equity Borrowing and
Household Behavior in the Early 2000s,” Federal Reserve Bank of Boston, Working Paper No.
09-7.
Crawford, Fordon W. and Eric Rosenblatt.
1995. “Efficient Mortgage Default Option Exercise:
Evidence from Loss Severity.” The Journal of Real Estate Research 10(5): 543-555.
Fitch Ratings, 2012. U.S.
Housing and Bank Balance Sheets Special Report, February 27, 2012.
Frye, John (2000a), “Collateral Damage,” Risk, April, 91-94.
Frye, John (2000b), “Collateral Damage Detected,” Federal Reserve Bank of Chicago,
Working Paper, Emerging Issues Series, October, 1-14.
Goodman, L., R. Ashworth, B. Landy, and K.
Yin. 2010. “Second Liens: How Important?” The
Journal of Fixed Income 20 (2), Fall: 19-30.
Gordy, Michael B.
and Bradley Howells. 2004. “Procyclicality in Basel II: Can We Treat the
Disease Without Killing the Patient?”
Greenspan, A.
and J. Kennedy. 2008.
“Sources and Uses of Equity Extracted from Homes.”
Oxford Review of Economic Policy 24 (1): 120-144.
Inside Mortgage Finance, 2013. Chart of the Week: Non-Agency MBS Characteristics. March
26, 2013.
Keys, Benjamin, Tanmoy Mukherjee, Amit Seru, and Vikrant Vig.
2010. “Did Securitization
Lead to Lax Screening?” The Quarterly Journal of Economics 125 (1): 307-362.
Keys, Benjamin, Amit Seru, and Vikrant Vig. 2012.
“Lender Screening and the Role of
Securitization: Evidence from Prime and Subprime Mortgage Markets.” Review of Financial
Studies (2012) 25(7): 2071-2108.
Ji, Lu and Yanan Zhang. 2010. “Basel II Loss Given Default Modeling of Seasoned Residential
Mortgage Loans,” Working Paper.
LaCour-Little, M., 2004.
“Equity Dilution: An Alternative Perspective on Mortgage Default.”
Real Estate Economics 32(3): 359-384.
LaCour-Little, Michael, Eric Rosenblatt, and Vincent Yao. 2010. “Equity Extraction by
Homeowners: 2000-2006.” Journal of Real Estate Research 32(1): 23-46.
LaCour-Little, Michael, Libo Sun, and Wei Yu.
2013. “The Role of Home Equity Lending in the
Recent Mortgage Crisis.” Real Estate Economics, forthcoming.
Economics Working Paper 2014-1
20
. LaCour-Little, Michael, Charles A. Calhoun, and Wei Yu. 2011. “What Role Did Piggyback
Lending Play in the Housing Bubble and Mortgage Collapse?” Journal of Housing Economics
20(2): 81-100.
Lekkas, Vassilis, John M.
Quigley, and Robert Van Order. 1993 “Loan Loss Severity and
Optimal Mortgage Default.” Journal of the American Real Estate Research and Urban
Economics Association 21(4): 353-371.
Mian, A.R., A. Sufi.
2009. “The Consequences of Mortgage Credit Expansion: Evidence from
the U.S. Mortgage Default Crisis.” Quarterly Journal of Economics, 124(4): 1449-1496.
Mian, A.R., A.
Sufi. 2011. “House Prices, Home Equity-Based Borrowing, and the U.S.
Household Leverage Crisis.” American Economic Review, 101: 2132-2156.
Pennington-Cross, Anthony.
2003. “Subprime and Prime Mortgages: Loss Distributions,”
unpublished manuscript, May.
Pennington-Cross, Anthony. 2006.
“The Duration of Foreclosure in the Subprime Mortgage
Market: A Competing Risks Model with Mixing,” Working Paper, Federal Reserve Bank of St.
Louis.
Qi, Min and Xiaolong Yang. 2009. “Loss Given Default of High Loan-to-Value Residential
Mortgages.” Journal of Banking and Finance 33(5): 788–799.
Saurina, Jesus and Gabriel Jimenez.
2006. “Credit Cycles, Credit Risk, and Prudential
Regulation.” International Journal of Central Banking, June 2006.
Schuermann, Til. 2004.
“What Do We Know About Loss Given Default?” Working Paper,
Wharton Financial Institutions Center.
Weicher, John C. 1997. The Home Equity Lending Industry.
The Hudson Institute: Indianapolis,
Indiana.
Economics Working Paper 2014-1
21
.