Jean-Roch Sibille - University of Liège Georges Hübner – University of Liège Third International Conference on Credit and Operational Risks Pricing CDOs with Correlated Arrival and Recovery Rates

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  Relationship between the Probability of Default (PD) and the Recovery Rate (RR) in a Monte Carlo framework.  Pricing of tranches from Collateralized Debt Obligations (CDO).  Product sensitive to the extreme losses and to the correlation structure inside the referenced portfolio. 1. Abstract

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  Asset-backed Security (ABS) where a pool of fixed income instruments are repackaged into highly rated securities.  Credit Derivatives allow financial institutions to dissociate the nominal amount of a loan from the associated credit risk.  Born in the late 80s to create liquid assets for banks.  The first CDO was created in 1987 by the famous Drexel Burnham Lambert, for a $100 million loan.  CBOs (CDO with Bonds) and CLOs (CDO with Loans) 2. Collateralized Debt Obligations 2.1. Definition

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  Rapid growth of the market with a short retrenching during the short recession in  Why the growth?  Repackaging and transferring of credit risk  You can pool whatever you want and still obtain investment grade  Diversification  Create liquidity  Increasing loan capacity  Reducing regulatory capital  Appearance of indices like ITraxx and CDX Growth in the Market

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner 2.3. Example Portfolio of Credit risks (Bonds, Loans,…) Bank € 1 billion Transfer of Assets Payment of par value of assets SPV Holds all the assets of originating bank Assets True Sale of Assets Bank’s Balance Sheet 1st Loss Piece retained by originator of the underlying Credits 1st Loss Piece (Equity) 2.5% BBB Tranche Investor 1.5% A Tranche Investor 1.5% AA Tranche Investor 2% AAA Tranche Investor 2.5% Super Senior Investor 90% Coupon payments and remaining par value at maturity Par value cash payment Risk Issuance of Notes or Bonds

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  50 underlying zero-coupon debts with notional of 1000 monetary units.  Defaults are simulated following a Poisson process.  Flat hazard rate structure of 2%.  3 tranches  Equity tranche 0% - 5%  Mezzanine tranche 5% - 15%  Senior tranche 15% - 100%  Maturity of 5 years.  20% default correlation across the whole portfolio.  20% correlation between RR and PD  Waterfall repayment at the maturity date.  4 different hypothesis about the recovery rate  1 million scenarios generated by the simulations 2.4. CDO Prototype

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner 2.5. Convergence

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  The recovery rate (RR) is the proportion of the amount due by the issuer of the debt that is recovered by the holder in case of default  Practically, three definitions are given to the RR.  Recovery of face value (RFV)  Recovery of Treasury value (RTV)  Recovery of market value (RMV)  Here we take the RTV for simplification purposes 3. Recovery Rate 3.1. Definition

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  A very convenient distribution for the RR is the beta distribution.  The distribution is bounded between 0 and 1.  There are only two parameters (alpha and beta) and they allow for various shapes of the distribution RR Distribution

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner Renaud and Scaillet (2004)

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner 3.3. Correlation between RR and PD  The relationship between RR and PD has been observed on the market and different authors have build credit risk model based on this hypothesis.  The objective in this paper is to introduce this correlation in a pricing model for CDOs.

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner 4. Pricing CDO  Use of a Gaussian copula model and Monte Carlo simulations  Permits a high level of flexibility: everything can vary (default intensity, interest rate, correlations,…).  Can be very time consuming: particularly with CDOs and big baskets.

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  Primarily a vector of correlated random numbers is taken from a copula function.  We take the univariate cumulative probability function of these numbers and then map these probabilities with the survival function which follows a Poisson process.  Therefore we can compute the time of default for each company i and compare it to the maturity of the option to determine if a credit event has appeared  For every simulation we have the times of default of every names in the portfolio of the CDO.  Knowing the times of default we can take into account the recovery rate (RR) to determine the losses Basic model

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  With the losses known for every simulation it is possible to construct a general probability distribution of the losses from the portfolio and realize a pricing of each tranche.  This model can be applied to a constant RR assumption or to a random RR following a beta distribution.

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner 4.2. Correlated model  The only thing we know about the state of the economy for a specific simulation are the vector of random numbers and their corresponding time of default.  If the random numbers are generated from a Gaussian copula, it is possible to orthogonalize them with a Cholesky factorization.  Being now independent random variables, we can consider the distribution of the sum of these variables as a proxy for the state of the economy.  The variables being normal and independent, the distribution of their sum is known.

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  Define  We obtain the probability  Where,

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  The objective now is to introduce the state of the economy (SE) in the distribution of the recovery rate.  If the RR are simulated from a beta distribution, the proposition is to determine part of the RR from the cumulative distribution of SE, the other part being random.  Where,  The mean of the distribution of SE being equal to 0, it has basically no effect on the general distribution of the RR.  But this is not true because all the names do not default.

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  The new objective will be to keep the correlation effect without changing the whole distribution of RR.  The solution proposed is to adapt the mean of the RR process.  Normally, whatever the correlation, the average total loss on the portfolio should be the same  We can adapt the mean of the RR to the increase of the total average loss to find back the same average loss even if the correlation effect is made.  To realize this, a new beta and alpha need to be determined for the beta distribution keeping the same standard deviation but with a new average.

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  4 different models (Constant, Random, Correlated and Modified Correlated RR) are tested on a virtual CDO which corresponds to market standard.  The comparison is made on the average losses that are computed for the various tranches (Equity, Mezzanine and Senior). 5. Results

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  A test is realized on a hundred different run of 10,000 simulations each to help determine material differences between models. 6. Significance test

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  Study the impact of a change in the default correlation and in the hazard rate. 7. Sensitivity Analysis

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner

 Pricing CDOs with Correlated Arrival and Recovery Rates J-R. Sibille & G. Hübner  4 different hypothesis on the distribution of the RR are tested in the pricing of a CDO and significant differences appear.  Possible explanation for the correlation smile.  The model needs to be confronted to market data. The calibration is being made on the series 6 of the iTraxx.  Other distribution could be tested to introduce the correlation of default. 8. Conclusion