  We show how inter-asset dependence information derived from market prices of
options can lead to improved model-free price bounds for multi-asset
derivatives. Depending on the type of the traded option, we either extract
correlation information or we derive restrictions on the set of admissible
copulas that capture the inter-asset dependencies. To compute the resultant
price bounds for some multi-asset options of interest, we apply a modified
martingale optimal transport approach. Several examples based on simulated and
real market data illustrate the improvement of the obtained price bounds and
thus provide evidence for the relevance and tractability of our approach.
