以2015～2022年沪深A股非金融上市公司为样本，探究年报问询函对共同机构所有权联结公司影子银行化的监管溢出效应。研究发现，上市公司收函后，与其有共同机构所有权联结的未收函公司影子银行化程度显著降低。机制分析表明，年报问询函通过提高联结公司监管效率，增加实业投资，抑制影子银行化。异质性分析发现，当共同机构投资者为长期型、其同行联结规模大、共同机构投资者竞争程度高、公司在投资组合中价值占比高或投资组合内重要公司收函时，该效应更显著，且对信用中介类影子银行业务监管溢出效应更强。

Based on the sample of China’s Shanghai and Shenzhen A-share non-financial listed companies from 2015 to 2022, this study examines the regulatory spillover effect of annual report inquiry letters on the shadow banking activities of companies connected through common institutional ownership. The research finds that after a listed company receives an annual report inquiry letter, the degree of shadow banking activities among its non-recipient peer companies with common institutional ownership significantly reduces. Mechanism analysis indicates that annual report inquiry letters curb shadow banking by enhancing the monitoring efficiency of connected companies, promoting investment in the real economy. Heterogeneity analysis reveals that this effect is more pronounced when the common institutional investors are long-term oriented, have a larger peer network, the competition among common institutional investors is intense, the company accounts for a significant portfolio weight, or key companies within the portfolio receive inquiry letters. Furthermore, the regulatory spillover effect is stronger on the shadow banking activities related to credit intermediation.