We study a generalization of the arc-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 Takàcs.We apply these results to the
pricing of exotic option contracts known as corridor derivatives.We then
discuss the inversion problem comparing different numerical methods.