Pricing options under stochastic volatility: a power series approach

In this paper we present a new approach for solving the pricing equations (PDEs) of European call options for very general stochastic volatility models, including the Stein and Stein, the Hull and White, and the Heston models as particular cases. The main idea is to express the price in terms of a power series of the correlation parameter between the processes driving the dynamics of the price and of the volatility. The expansion is done around correlation zero and each term is identified via a probabilistic expression. It is shown that the power series converges with positive radius under some regularity conditions. Besides, we propose (as in Alós in Finance Stoch. 10:353–365, 2006) a further approximation to make the terms of the series easily computable and we estimate the error we commit. Finally we apply our methodology to some well-known financial models.      

Internationalization and the evolution of corporate valuation

By documenting the evolution of Tobin's q before, during, and after firms internationalize, this paper provides evidence on the bonding, segmentation, and market-timing theories of internationalization. We find that Tobin's q does not rise after internationalization, even relative to domestic firms. Instead, q rises significantly before and during the internationalization year, but then falls sharply in the following year, quickly relinquishing the increases of the previous years. In decomposing these dynamics, we find that market capitalization rises before internationalization and remains high, while corporate assets increase during internationalization. The evidence supports the theory that financial internationalization facilitates corporate expansion, but challenges the theory that internationalization produces an enduring effect on q by bonding firms to a better corporate governance system.