Abstract:    Innovation is the source of shaping the competitive advantage of enterprises, and it is an important driving force leading economic development. At present, about 80% of Chinese listed companies have formed a group organization structure, and the allocation of resources between parent and subsidiary companies has become a topic of concern in theory and practice, especially the innovation structure of business group. The innovation structure refers to whether a conglomerate chooses to concentrate its R&D activities more in the parent company (referred to as "centralized innovation") or whether it prefers to decentralize them to its subsidiaries (referred to as "decentralized innovation"). In addition, in recent years, the number of stock pledges in China′s capital market has continued to increase. The leverage of stock pledge magnifies financial risks. Especially when the stock price falls, the risk of control transfer increases, which brings pressure on the capital market and in turn hinders the stable development of the real economy. Therefore, this paper makes use of the data advantages of parent-subsidiary innovation patents disclosed by Chinese listed companies to study stock pledge, which has strong practical value and theoretical significance for the dynamic adjustment of innovation structure.Based on the parent-subsidiary patent data disclosed by Chinese listed companies, this paper systematically explores the impact of stock pledge on the innovation structure in business groups and its specific mechanisms based on the perspective of the parent-subsidiary innovation structure. We find that stock pledge will make innovation more decentralized in subsidiaries, called decentralized innovation. The impact is stronger for firms with the increased pressures of stock price and performance. Furthermore, the impact of stock pledge on the decentralized innovation is more significant in non-state-owned companies, but there are no significant differences between the distribution of substantive innovation and strategic innovation. This study extended the scope of research on stock pledge and corporate innovation. On the one hand, by focusing on the issue of business group innovation structure, it helps to further elucidate the operational mechanism of innovation activities in group operation environment and makes a contribution to the study of business group and corporate innovation. On the other hand, this paper revealed the mechanism of the role of stock pledge on the innovation management model of business groups, which is an important supplement to the research on stock pledge and corporate innovation. It has certain reference significance for preventing systemic risks caused by stock pledge, and promoting high-quality innovation and development of China′s economy.The research conclusions have some important enlightenment value: First, for government regulators, it is necessary to prevent the "chaos" of the controlling shareholder′s stock pledge, strengthen the supervision of the stock pledge behavior, and fundamentally be wary of the controlling shareholder′s market value management. Second, for listed companies, they should strengthen the management of innovation activities within business groups, and flexibly consider achieving organic unity between enhancing innovation vitality and strengthening supervision. In order to enhance the vitality of innovation, business groups should appropriately adopt a decentralized innovation, reduce innovation risks and improve the efficient allocation of innovation resources.

Key words: capital market pressure, innovation structure, business group