In the framework of continuous-time, Ito processes models for financial mar
kets, we study the problem of maximizing the probability of an agent's weal
th at time T being no less than the value C of a contingent claim with expi
ration time T. The solution to the problem has been known in the context of
complete markets and recently also for incomplete markets; we rederive the
complete markets solution using a powerful and simple duality method, deve
loped in utility maximization literature. We then show how to modify this a
pproach to solve the problem in a market with partial information, the one
in which we have only a prior distribution on the vector of return rates of
the risky assets. Finally, the same problem is solved in markets in which
the wealth process of the agent has a nonlinear drift. These include the ca
se of different borrowing and lending rates, as well as "large investor" mo
dels. We also provide a number of explicitly solved examples.