A Procurement Auction Model Under Supplier Uncertainty

As business-to-business commerce shifts to the Internet, newer suppliers with cheaper but unreliable technologies enter the market place to win orders from firms by beating the price of their perfectly reliable (but expensive) competitors. The dilemma facing purchasing firms is the allocation of the tender across suppliers of varying supply reliability. We model the procurement problem as a sealed-bid auction where the buyer has to allocate purchases between an expensive but reliable supplier and a cheaper but unreliable supplier, and the suppliers specify prices for different proportions of the tender awarded to them. A unique feature of our model is that it allows the purchasing firm to reserve the right to change the size of the total tender awarded depending on the nature of the bids received from the suppliers. We prove that the set of Nash equilibrium outcomes coincides with the set of efficient outcomes, and for strictly convex cost functions, the outcome is unique. Further, we show that the possibility of implicit supplier collusion is strengthened in that the suppliers may structure their bids forcing the buyer to allocate the tender resulting in the worst-case (highest price) scenario for him. We also show that the Anton-Yao (A-Y, 1989) model can be interpreted as a limiting case of our model and that the efficient outcome derived in this paper is the only robust outcome in the A-Y model.