In a variety of industries ranging from agriculture to electronics and oil, procurement takes place through a combination of bilateral fixed-price contracts and open market trading among supply chain participants, which allows them to improve supply chain performance by utilizing new demand and cost information. The strategic behavior of the participants in these markets interacts with the way fixed-price contracts are formulated and significantly affects supply chain efficiency. In this paper, we develop a strategic model that allows endogenous price formation in an industrial spot market where supply chain participants have private information. Utilizing the model, we analyze the equilibrium of a dynamic game between a single supplier and multiple manufacturers who first contract with the supplier at a fixed price and then trade on a spot market. We study how such trading affects supply chain performance and show that it does not eliminate fixed-price contracting even though the fixed price is determined under inferior information. We find that it reduces prices, increases the quantities produced, and improves supply chain profits and consumer surplus. However, depending on the information structure of the supply chain, spot trading may make either the supplier or the manufacturers worse off. Our results show how the informational regime affects the profitability of supply chain participants and the allocation of quantities between the procurement venues. We show that beyond a threshold level, the effect of increasing supply uncertainty, or decreasing either the demand uncertainty or the information asymmetry among the manufacturers, is to increase the percentage procured on the spot market as well as the overall quantity procured and sold, and to decrease prices. As the number of manufacturers increases, procurement shifts from fixed-price contracting to spot trading and in the limit, the supply chain is both fully coordinated and informationally efficient. We also show that in many cases, the supplier may gain strategic advantage by sharing some of her cost information with the manufacturers.