We consider the seller's choice between sequential search and an auction when selling n homogeneous units of a good in the presence of informational asymmetries, discounting, and transaction costs. Our analysis shows that the expected return per unit from sequential selling decreases in n, the number of units being sold. For the auction with suitable restrictions, the expected return per unit increases in n. Thus, sequential search is the preferred institution if n is small, whereas the auction is preferred if n is large. Historical details of the evolution of livestock markets closely fit our theoretical results.