همکاری در حین عدم اطمینان: ارزیابی ارزش به اشتراک گذاری ریسک و تعیین بهترین قانون به اشتراک گذاری ریسک برای  عوامل با کسب و کار از قبل موجود و نگرش های ریسک متفاوت  Cooperation under uncertainty: Assessing the value of risk sharing and determining the optimal risk-sharing  rule for agents with pre-existing business and diverging risk attitudes

1. Introduction The selection of partners in a joint venture and the allocation of risk among them are important decisions that have a deep impact on the success of the project. However, the existing methods in the literature only consider the agent’s risk aversion, leading to the least risk-averse agent taking a higher share of the risk. However, determining the best risk-sharing approach should take other factors into account such as the agent’s pre-existing businesses. This paper answers this question, developing a model to determine the value of risk sharing – that is, how much value the coalition brings with respect to the project being developed by a single partner. Contrary to existing approaches, our developed value of risk sharing considers the agents’ pre-existing business and their correlation to the joint venture, together with their risk attitudes. The model provides valuable insights for the most favourable design of a coalition and the risk-sharing contract in order to get the most of the benefits of cooperation. Cooperation is even more important in infrastructure projects given their high capital intensity, which makes it necessary to form partnerships face the needs for investment in an efficient way. Specifically, the energy sector has recently experienced an increased need for cooperation which we would like to highlight, as it provides a further specific context for this need. Agents in the energy sector are increasingly seeking cooperation to cope with the competitive and complex energy landscape caused by forces such as liberalization, deregulation, renewable energy integration, and climate policies (Ligtvoet, 2013). This can be seen in several large scale joint infrastructure project initiatives and plans. For example, in the USA, regional transmission operators are cooperating to develop inter-regional electricity transmission lines to facilitate the integration of renewable energy sources that span across multiple regions (MIT Energy Initiative, 2011). In Europe, bordering transmission operators are cooperating to invest in cross-border transmission to facilitate electricity market integration (Brancucci Martínez-Anido, 2013). Moreover, new regulatory frameworks are being introduced to encourage cooperation in electricity markets integration (Böckers et al., 2013), renewable energy integration (EU Commission, 2006), electricity and gas infrastructure development and upgrade (Henry et al., 2014; Brancucci Martínez-Anido, 2013), energy efficiency (Nauleau et al., 2015), and CO2 emission reduction (RCI, 2011). The rationale for cooperation in infrastructure projects is multiple: it enables agents to minimize the effects of uncertainty by aligning their interests (Ligtvoet, 2013); provides strategic advantages such as the ability to achieve objectives faster, getting access to know-how or to markets, cost advantages, transfer or complementarity of technologies, and economies of scale (Williamson, 1979; Bronder and Pritzl, 1992; Guoa et al., 2014). However, cooperation is not always straightforward, and various uncertain factors expose parties to different kinds of risks (Lam, 1999; EU Commission, 2006). On the one hand, large-scale infrastructure projects are particularly subject to risk due to large initial costs, high irreversibility (sunk costs), and long-term durability of assets (Lam, 1999; Boatenga et al., 2015). On the other hand, cooperation involving infrastructure (and energy infrastructure in particular) is complex as multiple agents are involved with different objectives and constraints. By its own nature, cooperation is a multi-motive game. Because each party displays a rational behaviour, there are considerable costs and risks involved in the decision to join a project (Williamson, 1979; Nooteboom, 2000). The presence of endogenous uncertainty (e.g. strategic behaviour) (Berger and Hershey, 1994; Grundy, 2000) and exogenous uncertainty (e.g. technology, market, regulatory changes) often lead to a deadlock in which decision-making stagnates as parties become increasingly risk averse and are afraid to ‘bet on the wrong horse’ (McCarter et al., 2010; Gong et al., 2009). Therefore, with incentives on one hand and costs and risks on the other, the challenges in most infrastructure development cooperation projects are: (1) How will the associated risk and value be shared among the partners? (2) How should we structure contracts to enhance synergies at an acceptable level of risk?