Economics - Research Publications
Permanent URI for this collection
Search Results
1 - 2 of 2
-
ItemThe integrated square-root process( 2001-11)The square-root process has been used to model interest rates and stochastic volatility. This paper studies some of its properties, particularly those of the integral of the process over time. After summarizing the properties of the square-root process, the Laplace transform of the integral of the square-root process is derived. Three methods for the computation of the moments of this integral are given, as well as some properties of the density of the integral. The last section studies the relationship between the Laplace transforms of a variable and of its reciprocal, a topic which arises in the previous analysis and elsewhere. An application to the generalized inverse Gaussian distribution is given
-
ItemAsian and Basket Asymptotics( 2002-07)The pricing of Asian or basket options is directly related to finding the distributions of sums of lognormal random variables. There is no general explicit formula for those distributions. This paper looks at the limit distributions of sums of lognormal variables when volatility, or maturity, tends to either 0 or to infinity. The limits obtained are either normal or lognormal, depending on the normalization chosen. This justifies the lognormal approximation, much used in practice, and also gives an asymptotically exact distribution for averages of lognormals with a relatively small volatility; it has been noted that all the analytical pricing formulas for Asian options perform poorly for small volatilities. Asymptotic formulas are also found for the moments of the sums of lognormals. Results are given for both discrete and continuous averages.