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Explore the use of high-performance computing in the financial service industry for credit risk management, pricing of structured financial products, and statistical estimation and calibration of models.
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From Monte Carlo to Wall Street Dr. D. Egloff Head Financial Computing Zürcher Kantonalbank
Agenda • HPC in Finance • Credit portfolio risk • Credit risk and economic capital • Related HPC problems and solutions • Pricing of financial contracts • Next generation lattice models • Related HPC problems and solutions
HPC in Financial Service Industry • Problem domain • Risk management, particularly of rare events such as in credit and operational risk • Pricing of structured financial products • Statistical estimation and calibration of models for forecasting, pricing, risk management • Methods • Simulation (Monte Carlo and refinements) • Large scale optimisation • Large scale linear algebra • Partial differential equations • Fourier transform
Agenda • HPC in Finance • Credit portfolio risk • Credit risk and economic capital • Related HPC problems and solutions • Pricing of financial contracts • Next generation lattice models • Related HPC problems and solutions
Loss Risk capital Profit Less than x% ny today 1y 2y Credit Risk and Capital • For a portfolio of credit exposures • Simulate profit and loss over multiple periods • Reserve capital to cover x% of the worst outcomes
The Price of Realism Realistic implementation of a credit portfolio risk solution requires • Dependent defaults of obligors • Long term view over multiple years • Inclusion of credit deterioration over time • Inclusion of contract cash flow details • Ability to aggregate and disaggregate Calculations become computationally demanding
Parallel Monte Carlo Simulation • Monte Carlo is embarrassingly parallel • Runs efficiently on distributed memory clusters • Calculations generally not latency bound • sample generation generally takes longer than statistical analysis of samples • Simple communication pattern • send samples back to one or several master nodes for analysis • Analysis of extreme tail risks require improvements • Variance reductions • Adaptive schemes based on stochastic optimization
Adaptive Monte Carlo • Use simulated samples to improve sampling distribution • Fundamental difference to non-adaptive MC • weighted samples • non-iid sampling • Mathematics of convergence and error analysis much more difficult • Based on stochastic optimization • Parallel implementation • Communication pattern becomes more involved
Issues of Parallel Simulation How to statistically aggregate massive simulation data? • OLAP aggregation does not scale because of IO bandwidth limitations, in particularly if data stride is large • Single aggregation node may not be sufficient • Tree like aggregation requires more complex communication • Many to many communication scheme • Iterative algorithms required to calculate statistics • Easy for means and moments, more difficult for quantiles, marginal risk contributions, ...
ImplementationSoftware – Hybrid design • Performance critical algorithms are implemented in C++ • Fast • Python is used for non-performance-critical sections • Dynamic and expressive • Very efficient development cycle • Ideal for prototyping
ImplementationCluster distribution • Separation of risk factor dynamics and instrument valuation from statistical aggregation • The simulation process is monitored by a management node • The number of nodes for statistical aggregation depends on the number and type of statistics required • Communication through efficient MPI
Agenda • HPC in Finance • Credit portfolio risk • Credit risk and economic capital • Related HPC problems and solutions • Pricing of financial contracts • Next generation lattice models • Related HPC problems and solutions
What is Pricing? • Fundamental theorem of asset pricing • No arbitrage pricing • Under suitable assumptions prices are expectations under a so called risk neutral measure
Numerical Pricing Methods • Analytical • Stringent assumptions, small model variety, most prominent Black Scholes model • Semi-analytical • Exploit special structure (affine, quadratic) • Expansion and perturbation techniques • Reduction to ODE (often Riccati) • Numerical • Monte Carlo • Trees • PDE and PIDE • Transform methods i.e., FFT, Laplace • Lattice methods
Lattice Methods States mapped to a lattice Markov structure Model specification in terms of generator matrix, i.e. infinitesimal transition probabilities 5‘000 to 10‘000 states Dense matrices t2 t3 t1