A (v, k, i) trade of volume m consists of two disjoint collections Tl and T 2 , each of m k-subsets (blocks) of a v-set V, such that each i-subset of V is contained in the same number of blocks of TI and of T 2 • A (v, k, i) trade is simple if it has no repeated blocks, and has index i if some i-subset occurs in i blocks of TI but no i-subset occurs in more than i blocks. In this paper we investigate the spectrum (that is, the set of possible vol urnes) of simple (v, k, 2) trades of index i.