Abstract: A method and system for dynamic combinatorial auctions employing bid composition restrictions is disclosed. Three exemplary types of bid composition restrictions, which may be applied either singly or in combination, are disclosed: non-additive activity restrictions, subset restrictions, and superset restrictions. These restrictions produce more efficient auction outcomes by placing extra constraints on bidders who specify larger combinations in their bids, thereby penalizing attempts at strategic bidding without ruling out genuine attempts to avoid an exposure problem.