Before revision:  Finally we provide a dual representation  in terms of weakly open sets of probability measures, which highlights the robust nature of our approach .
After revision:  These results are obtained by adopting a technical filtration enlargement and by constructing a universal aggregator of all arbitrage opportunities. We further introduce the notion of market feasibility and provide its characterization via arbitrage conditions. We conclude providing a dual representation in terms of weakly open sets of probability measures, which highlights the robust nature of our approach .