2,665 research outputs found
Computing Tails of Compound Distributions Using Direct Numerical Integration
An efficient adaptive direct numerical integration (DNI) algorithm is
developed for computing high quantiles and conditional Value at Risk (CVaR) of
compound distributions using characteristic functions. A key innovation of the
numerical scheme is an effective tail integration approximation that reduces
the truncation errors significantly with little extra effort. High precision
results of the 0.999 quantile and CVaR were obtained for compound losses with
heavy tails and a very wide range of loss frequencies using the DNI, Fast
Fourier Transform (FFT) and Monte Carlo (MC) methods. These results,
particularly relevant to operational risk modelling, can serve as benchmarks
for comparing different numerical methods. We found that the adaptive DNI can
achieve high accuracy with relatively coarse grids. It is much faster than MC
and competitive with FFT in computing high quantiles and CVaR of compound
distributions in the case of moderate to high frequencies and heavy tails
Calculation of aggregate loss distributions
Estimation of the operational risk capital under the Loss Distribution
Approach requires evaluation of aggregate (compound) loss distributions which
is one of the classic problems in risk theory. Closed-form solutions are not
available for the distributions typically used in operational risk. However
with modern computer processing power, these distributions can be calculated
virtually exactly using numerical methods. This paper reviews numerical
algorithms that can be successfully used to calculate the aggregate loss
distributions. In particular Monte Carlo, Panjer recursion and Fourier
transformation methods are presented and compared. Also, several closed-form
approximations based on moment matching and asymptotic result for heavy-tailed
distributions are reviewed
A general methodology to price and hedge derivatives in incomplete markets
We introduce and discuss a general criterion for the derivative pricing in
the general situation of incomplete markets, we refer to it as the No Almost
Sure Arbitrage Principle. This approach is based on the theory of optimal
strategy in repeated multiplicative games originally introduced by Kelly. As
particular cases we obtain the Cox-Ross-Rubinstein and Black-Scholes in the
complete markets case and the Schweizer and Bouchaud-Sornette as a quadratic
approximation of our prescription. Technical and numerical aspects for the
practical option pricing, as large deviation theory approximation and Monte
Carlo computation are discussed in detail.Comment: 24 pages, LaTeX, epsfig.sty, 5 eps figures, changes in the
presentation of the method, submitted to International J. of Theoretical and
Applied Financ
Non-Gaussian gravitational clustering field statistics
In this work we investigate the multivariate statistical description of the
matter distribution in the nonlinear regime. We introduce the multivariate
Edgeworth expansion of the lognormal distribution to model the cosmological
matter field. Such a technique could be useful to generate and reconstruct
three-dimensional nonlinear cosmological density fields with the information of
higher order correlation functions. We explicitly calculate the expansion up to
third order in perturbation theory making use of the multivariate Hermite
polynomials up to sixth order. The probability distribution function for the
matter field includes at this level the two-point, the three-point and the
four-point correlation functions. We use the hierarchical model to formulate
the higher order correlation functions based on combinations of the two-point
correlation function. This permits us to find compact expressions for the
skewness and kurtosis terms of the expanded lognormal field which can be
efficiently computed. The method is, however, flexible to incorporate arbitrary
higher order correlation functions which have analytical expressions. The
applications of such a technique can be especially useful to perform
weak-lensing or neutral hydrogen 21 cm line tomography, as well as to directly
use the galaxy distribution or the Lyman-alpha forest to study structure
formation.Comment: 20 pages, 2 figures; accepted in MNRAS 2011 August 22, in original
form 2010 December 14 published, Publication Date: 03/201
Formation and Evolution of Primordial Black Hole Binaries in the Early Universe
The abundance of primordial black holes (PBHs) in the mass range can potentially be tested by gravitational wave observations due to
the large merger rate of PBH binaries formed in the early universe. To put the
estimates of the latter on a firmer footing, we first derive analytical PBH
merger rate for general PBH mass functions while imposing a minimal initial
comoving distance between the binary and the PBH nearest to it, in order to
pick only initial configurations where the binary would not get disrupted. We
then study the formation and evolution of PBH binaries before recombination by
performing N-body simulations. We find that the analytical estimate based on
the tidally perturbed 2-body system strongly overestimates the present merger
rate when PBHs comprise all dark matter, as most initial binaries are disrupted
by the surrounding PBHs. This is mostly due to the formation of compact N-body
systems at matter-radiation equality. However, if PBHs make up a small fraction
of the dark matter, , these estimates become more
reliable. In that case, the merger rate observed by LIGO imposes the strongest
constraint on the PBH abundance in the mass range . Finally,
we argue that, even if most initial PBH binaries are perturbed, the present
BH-BH merger rate of binaries formed in the early universe is larger than
Comment: 32pages, 12 figures, typos corrected, references added, figures
updated, matches version published in JCA
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General closed-form basket option pricing bounds
This article presents lower and upper bounds on the prices of basket options for a general class of continuous-time financial models. The techniques we propose are applicable whenever the joint characteristic function of the vector of log-returns is known. Moreover, the basket value is not required to be positive. We test our new price approximations on different multivariate models, allowing for jumps and stochastic volatility. Numerical examples are discussed and benchmarked against Monte Carlo simulations. All bounds are general and do not require any additional assumption on the characteristic function, so our methods may be employed also to non-affine models. All bounds involve the computation of one-dimensional Fourier transforms; hence, they do not suffer from the curse of dimensionality and can be applied also to high-dimensional problems where most existing methods fail. In particular, we study two kinds of price approximations: an accurate lower bound based on an approximating set and a fast bounded approximation based on the arithmetic-geometric mean inequality. We also show how to improve Monte Carlo accuracy by using one of our bounds as a control variate
Modelling FX smile : from stochastic volatility to skewness
Imperial Users onl
Applications of Laplace transform for evaluating occupation time options and other derivatives
The present thesis provides an analysis of possible applications of the Laplace Transform (LT) technique to several pricing problems. In Finance this technique has received very little attention and for this reason, in the first chapter we illustrate with several examples why the use of the LT can considerably simplify the pricing problem. Observed that the analytical inversion is very often difficult or requires the computation of very complicated expressions, we illustrate also how the numerical inversion is remarkably easy to understand and perform and can be done with high accuracy and at very low computational cost.
In the second and third chapters we investigate the problem of pricing corridor derivatives, i.e. exotic contracts for which the payoff at maturity depends on the time of permanence of an index inside a band (corridor) or below a given level (hurdle). The index is usually an exchange or interest rate. This kind of bond has evidenced a good popularity in recent years as alternative instruments to common bonds for short term investment and as opportunity for investors believing in stable markets (corridor bonds) or in non appreciating markets (hurdle bonds). In the second chapter, assuming a Geometric Brownian dynamics for the underlying asset and solving the relevant Feynman-Kac equation, we obtain an expression for the Laplace transform of the characteristic function of the occupation time. We then show how to use a multidimensional numerical inversion for obtaining the density function. In the third chapter, we investigate the effect of discrete monitoring on the price of corridor derivatives and, as already observed in the literature for barrier options and for lookback options, we observe substantial differences between discrete and continuous monitoring. The pricing problem with discrete monitoring is based on an appropriate numerical scheme of the system of PDE's.
In the fourth chapter we propose a new approximation for pricing Asian options based on the logarithmic moments of the price average
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