Corridor options and arc-sine law

We study a generalization of the are-sine law In particular we provide new results about the distribution of the time spent by a BM with drift inside a band, giving the Laplace transform of the characteristic function. If one of the extremes of the band goes to infinity, our formula agrees with the results given in Akahori and Takacs. We apply these results to the pricing of exotic option contracts known as corridor derivatives. We then discuss t he inversion problem comparing different numerical methods.