Before revision:  We find that, in repeated call auctions , nonstrategic bidding leads to a sequence of allocations that converges to individually rational Pareto allocations.
After revision:  We find that, under nonstrategic bidding, the double auction clears with zero trades precisely when the agents' current holdings are on the Pareto frontier. More interestingly, the double auctions implement Adam Smith's "invisible hand" in the sense that, when starting from disequilibrium, repeated double auctions lead to a sequence of allocations that converges to individually rational Pareto allocations.