Related guarantee is strongly favored by Chinese firms, with over 97% listed firms having related guarantee. First, related parties have incentives to seek the optimal allocation of credit resources among all parties as they have more consistent interest demands. Second, related parties have better understandings of each other′s operations, real risk level, and repayment capacity, compared with banks. Finally, related guarantee can reduce guarantee cost. Commercial guarantee not only requires guarantee fee, but also counter-guarantee at times. However, related guarantee reduces the guarantee cost and improves the guarantee efficiency greatly. 

At the same time, related guarantee has negative effects as well. The "Delong System" and the "Zhongrong Xinjia Incident" in 2013 have brought profound lessons to the capital market. For one thing, only related parties failing to meet banks′ funding thresholds, will be required additional guarantees. In fact, when a listed firm provides guarantee for its affiliated party, it indicates a bearing of financing risk beyond repayment capacity of the affiliated party. For another, according to the asset substitution hypothesis, wealth increment will be transferred from creditors to shareholders when replacing low-risk assets with high-risk assets. Therefore, even if the risk level of related parties exceeds the level that creditors can bear, shareholders of listed firms still have the incentive to use their own advantages to help related parties cover up their deficiencies and obtain bank loans by one of their important means, related guarantee.

The academic and practical practitioners have discussed the technological innovation of enterprises from many different macro and micro perspectives, but the impact of guarantee for related parties on innovation has not been paid enough attention. Sampled on A-Share listed firms from 2007 – 2016, this study analyzes the impact of related guarantees on corporate innovation and its mechanism theoretically, and conducts empirical tests based on large sample data by OLS, quantile regression, Poisson regression and 2SLS models. 

The research finds that the guarantees for related parties significantly inhibit the innovation activities of firms. The more related guarantees provided by firms, the lower R&D investment and patent application of firms will be. The separation between control and cash flow rights aggravates agency problem between major and minor shareholders，exacerbating the restraining effect of related guarantee on the technological innovation of firms. On the contrary, mortgaged property can effectively reduce the risk caused by related guarantee and reduce the tunneling opportunity of major shareholders. Consequently, the value of the assets available for guarantee helps mitigate the negative effect of related guarantees on innovation. Additional analysis also suggests that the mechanisms of influence of guarantees for related parties on innovation mainly consist of transfer of risk and aggravating the tunneling of major shareholders. The conclusions are still valid after enough robustness tests and addressing endogeneity.

This paper enriches the analysis framework of enterprise innovation, and provides some revelations for the managers and market regulators. First of all, as an important mechanism of credit enhancement, related guarantee effectively alleviates the "financing difficulty" faced by firms. However, it also brings serious risks to firms. In the process of providing related guarantee, firms must strengthen the risk assessment of affiliated parties, assure the authenticity and transparency of related parties′ information, and eliminate the "excessive financing" of affiliated parties. Second, the related guarantee may become a tool for the tunneling of major shareholders. Accordingly, the market regulatory authorities should strengthen the control of the related guarantee and punish the opportunism of major shareholders severely. Third, for firms with a high degree of separation of cash flow rights and control rights and a low value of the mortgaged property, they should pay special attention to related guarantee and take precise measures.