This study analyzes the network structures of institutional shareholders and examines the influence of institutional investor cliques on corporate innovation. Our empirical results reveal that institutional investor cliques significantly enhance both innovation input and output. To mitigate endogeneity concerns and establish causality, we adopt multiple empirical strategies. Further evidence suggests that the beneficial impact of institutional investor cliques on firm innovation can be attributed to increased innovation investment efficiency, enhanced employee productivity, reduced information asymmetry, and decreased managerial myopia. Additionally, we find that the positive effect of institutional investor cliques on firm innovation is more pronounced in non-state-owned enterprises and is particularly evident in firms with severe agency conflicts, CEO duality issues, highly competitive product markets, and for firms that have low stock liquidity.

Distinct from existing studies on general institutional investors and institutional investor cliques, this study examines how common institutional owners, who simultaneously hold more than 5% equity blocks in at least two publicly traded firms within the same industry, influence firms’ bad mergers and acquisitions (M&As) in China. Contrary to the “conspiracy tort” view, according to which common institutional owners are more likely to vote for bad M&A deals to pursue internalized gains from industry portfolios (Antón et al., 2022b), our results strongly support the “synergy governance” view, according to which common institutional owners perform more actively and effectively in monitoring against bad M&As and improving M&A quality. There is further evidence that common institutional owners with greater peer linkages and industry power and longer-term holdings are more likely to oppose deals with negative acquirer returns. Finally, we find that the effect of common institutional ownership on M&As is more pronounced among firms with stronger earnings management, moderate stock return synchronicity, less management shareholding and higher management expenses. The results are consistent with the “synergy governance” hypothesis whereby common institutional owners are able to leverage their advantages of industry information and supervisory experience to improve the information environment and corporate governance of the firms they hold. Overall, in China’s market, common institutional owners play an active external governance role and effectively improve M&A quality.