《上市公司分拆所属子公司境内上市试点若干规定》（简称《若干规定》）于2019年底发布后，国内掀起A股分拆上市的热潮。分拆上市的“行业效应”是指分拆上市事件对于行业内其他公司股价产生的短期影响。基于国内外学者的相关理论基础，分拆上市公告对于母子公司行业的其他公司存在一定程度的行业效应。母子公司的可比公司系与母子公司相关性较高的行业公司群体，本文将其作为研究对象，综合运用实证分析和案例分析方法，研究A股上市公司分拆子公司于境内上市（简称“A拆A”）公告的行业效应，得出以下研究结论：关于分拆上市公告行业效应的存在性，本文研究发现：1）首次发布分拆上市公告：对于母公司行业可比公司股价存在显著负向的行业效应，即：竞争效应；对于子公司行业可比公司股价存在一定程度的竞争效应，分拆上市信息存在提前泄露的可能性。2）发布分拆上市通过审核公告：对于母公司行业可比公司股价存在显著的竞争效应，且竞争效应存在前移现象，此外，相比首次发布分拆上市公告窗口期，发布通过审核公告窗口期的异常收益率较低；子公司可比公司的股价在通过审核公告的窗口期内未受到显著的负向或正向影响。关于分拆上市特征对于竞争效应的影响，本文研究发现：同行业分拆上市公告对母公司可比公司股价的负面影响程度更高，进一步地，母公司与子公司行业相关性越高，分拆上市公告对母公司可比公司的股价负面影响程度越高，竞争效应越明显，且上述结论具有一定的稳健性。分拆上市板块、分拆规模和企业性质均不显著影响分拆上市公告的竞争效应。关于分拆上市的广义行业效应，本文采用案例分析的方式研究行业溢出效应。中国铁建成功分拆铁建重工上市后，母子公司的核心竞争力在各方面均有所提升。此后，中国铁建的同行业可比公司中国中铁、中国能建亦先后发布分拆上市预案。中国中铁成功分拆高铁电气上市后，实现估值重塑，并大幅提升核心竞争力；中国能建的子公司易普力虽然暂未上市，但预计分拆上市后将提升核心竞争力、实现估值重塑，并有望通过资本运作冲击行业龙头地位。中国铁建率先发布分拆上市预案和上市后母子公司的亮眼表现发挥积极的表率作用，为行业内其他公司的分拆上市建立积极的行业溢出效应。

After the release of the Regulations at the end of 2019, the A-share equity carve-out has started in China. Industry effect refers to the short-term impact of equity carve-out events on the share prices of other companies in the industry. Based on the relevant theoretical basis and the research conclusions of scholars, the carve-out announcement has a certain industry effect on the share prices of other companies in the parent and subsidiary industry. The comparable companies are industry companies with high correlation with the parent and subsidiary companies. This paper takes them as the research objects and uses the method of empirical analysis to study the industry effect of A-share equity carve-out announcement. The following research conclusions are drawn:About the industry effect of A-share equity carve-out announcement, the study found that: 1) During the first equity carve-out announcement window period, the share price of the parent comparable company is significantly negatively affected, which is competitive effect, subsidiary comparable companys’ share price by a certain degree of negative impact, and the carve-out information exists the possibility of a leak. 2) During the window for issuing the approval announcement, the share price of the parent comparable company is significantly negatively affected. At the same time, compared with the first announcement, the abnormal return of the approval announcement is more obvious. In addition, the industry effect is moving forward. There is no significant negative or positive influence on the share price of subsidiary comparable companies during the window period of issuing the approval announcement.As for the impact of equity carve-out characteristics on the competitive effect, this paper finds that: the higher the industry correlation between the parent company and subsidiary company is, the higher the degree of negative impact of carve-out announcement on the share price of parent comparable companies is. The competitive effect of carve-out announcement is not significantly affected by the listed sector, carve-out scale and enterprise nature.As for the industry effect of equity carve-out not limited to share price in a broad sense, this paper uses the method of case study to study the industry spillover effect. After the successful equity carve-out, the core competitiveness of China Railway Construction Corporation Limited (CRCC) and China Railway Construction Heavy Industry Corporation Limited has been improved in all aspects. Later on, comparable companies, China Railway Group Limited and China Energy Engineering Corporation Limited also issued equity carve-out plans. CRCC took the lead in releasing the equity carve-out plan and the outstanding performance after equity carve-out played a positive role in setting the industry spillover effect for other companies in the industry.