Consumer strategies limiting the monopolist's power: multiple and joint purchases

I characterize the menu of bundles (price-quantity combinations) offered by a monopolist when consumers can buy several bundles, share bundles with ot hers, or do beds in a two-type setting, I find that although perfect arbitr age prevents any price discrimination, partial arbitrage in the form of mul tiple or joint purchases may actually lead to more pronounced price discrim ination than when consumers ean only pick one single bundle. further, clear predictions emerge for the price pattern, contrasting with the existing li terature: with multiple purchases only, the firm offers strict quantity dis counts; with joint purchases only, discounts are infeasible.