Abstract: Based on the benchmark newsvendor model, this paper adds the time competition factor, establishes the model and analyzes the results. It is proved by our research that the buyback contract cannot achieve the coordination of the supply chain when the retailer makes the decision on the order quantity and the effort level at the same time. The paper proposes a new default sharing contract, and proves that the default sharing contract and buyback contract portfolio can make retailers and suppliers obtain Pareto improvement and achieve the coordination of supply chain. The results can provide an effective guide for the signing of contracts for seasonal merchandise retailers and suppliers in the process of cooperation.

Key words: seasonal goods, newsvendor model, time competition, supply chain coordination