We reconsider the microeconomic foundations of financial economics under Knightian Uncertainty. In a general framework, we discuss the absence of arbitrage, its relation to economic viability, and the existence of suitable nonlinear pricing expectations. Classical financial markets under risk...

The dual representation of the martingale optimal transport problem in the Skorokhod space of multi dimensional cadlag processes is proved. The dual is a minimization problem with constraints involving stochastic integrals and is similar to the Kantorovich dual of the standard optimal transport...

An agent can invest in a high-yield bond and a low-yield bond, holding either long or short positions in either asset. Any movement of money between these two assets incurs a transaction cost proportional to the size of the transaction. the low-yield bond is liquid in the sense that wealth...

We analyze numerically the superreplication problem and the associatedhedging strategy in an illiquid binomial market. We prove theexistence of an optimal feedback strategy for European and barrier optionsand compute it numerically by means of a dynamic programmingprinciple. We exhibit that the...

In a market with transaction costs, generally, there is no nontrivial portfolio that dominates a contingent claim. Therefore, in such a market, preferences have to be introduced in order to evaluate the prices of options. The main goal of this article is to quantify this dependence on...

We prove limit theorems for the super-replication cost of European options in a Binomial model with friction. The examples covered are markets with proportional transaction costs and the illiquid markets. The dual representation for the super-replication cost in these models are obtained and...

We introduce a notion of volatility uncertainty in discrete time and define the corresponding analogue of Peng’s G-expectation. In the continuous-time limit, the resulting sublinear expectation converges weakly to the G-expectation. This can be seen as a Donsker-type result for the G-Brownian...

In the list of possible scapegoats for the recent financial crises, mathematics, in particular mathematical finance has been ranked, without a doubt, as the first among many and quants, as mathematicians are known in the industry, have been blamed for developing and using esoteric models which...