Abstract: In recent years, the Public-Private Partnership model has been vigorously promoted in order to efficiently provide infrastructure services that meet public needs. Long period and high risk are existed in PPP transport projects. In addition to the initial capital of the construction period, the subsequent operation period also requires high operation and maintenance costs. The financing problem becomes the key to the success of PPP projects due to the huge investment. As the initiator, government needs to provide certain guarantee for the project to attract the participation of social capital. However, over-guarantee lacks incentives for social capital. Once a large amount of debt default occurs, it will cause a huge financial burden.
In view of the above problems, domestic and foreign scholars have conducted extensive studies on PPP project refinancing and the ratio of government guarantee, but few studies have been conducted on the specific design and pricing of innovative market-oriented refinancing products. Referring to the mechanism of government guarantee and contingent capital, a structured product embedded with contingent face value increase and decrease clauses collateralized by future operating earnings is designed. When the project income does not reach the lower threshold, the loss is absorbed by the write-down clause. When the project development exceeds the expected upper threshold, the excess earnings are shared by the write-up clause. Merton model in structural approach is used to solve the pricing problem under the risk-neutral world.
It is divided into the following steps in specific:Firstly, the contingent clauses are designed on the basis of the project revenue bond by coordinating the interests of stakeholders. Secondly, the model is established based on traffic volume variation, which is the most important determinant of the project income. Finally, taking a PPP transport project as an example, the product price and risk spread are computed and sensitivity analysis of some important parameters are carried out to explore the economic effect. The example is selected from the project management library of China Public Private Partnerships Center. Due to the confidentiality of franchise agreement, this paper only refers to the basic framework of the expressway PPP project case, and makes reasonable assumptions based on the feasibility analysis report and bidding documents.
A refinancing product combining the project revenue bond and contingent clauses is proposed, which makes up for the deficiency of insufficient research on product design and pricing. The results show that the product can effectively reduce government guarantee burden as well as financing cost. Compared with ordinary project revenue bonds, the product can reduce the government guarantee burden. Compared with ordinary write-down bonds, it can reduce the issuing cost. It is conducive to achieve the revenue sharing-risk sharing incentive compatibility situation between the issuers and the investors. Under the design of clauses and parameters, the risk spread of PPP refinancing product is positively correlated with the risk-free interest rate, the lower guarantee threshold coefficient and the write-down ratio, and negatively correlated with the volatility of traffic volume. It provides a reference for the reasonable selection of some parameters and product risk management.

Key words: PPP transport project, government guarantee value, contingent clause, structured product pricing