我国公募基金行业已发展二十余年，无论是行业的供给端还是需求端都经历了高速发展的繁荣阶段。随着宏观经济周期的波动和新冠疫情等突发因素对各行各业的冲击，公募基金行业逐渐步入了稳健发展、自我革新的阶段，期间行业的问题不断暴露出来，上至国家层面下至基金经理个体层面都需要对这些问题给予高度关注并逐一解决。在诸多问题之中，本文关注的是基金经理管理多只基金的“一拖多”现象。这一现象背后的原因多样，包括行业人才数量有限及基金公司为吸引投资者而过度追捧明星基金经理等。而本文认为，基金经理的专注度有限，管理多只基金可能会分散其精力，即使有足够强的主动管理能力，也有可能导致基金业绩不佳。这一研究可以为基金公司对其内部基金经理团队的管理和激励机制建设提供一定的依据，也说明了公司和国家层面对这一现象进行整治和改善的必要性。本文使用2003年-2022年间的基金与基金经理相关数据，构建了三个对基金经理专注度进行考察的代理变量：基金平均数量、平均外部资产、资产规模占比，其中后两个为规模层面的代理变量，对过往研究中的基金数量层面的单一维度作了补充，探究了基金经理管理多只基金的背景下，基金经理专注度与基金业绩之间的关系。研究结果发现，基金经理有限关注度会对基金业绩产生负面影响，并且这一外部资产效应虽然不如内部基金规模效应对基金业绩的影响显著，但二者仍在同一量级，因此这一外部效应值得引起重视。另外，通过分组回归还发现，不同投资策略下基金经理专注度对基金业绩的影响有所差异，其中主动型基金受到基金经理专注度的影响更加显著。这一结论将帮助基金经理和基金公司更好地进行任务分配并得到更好的整体业绩，从而对投资者、基金公司以及公募基金行业都有长远的正面影响。

China‘s public fund industry has been developing for more than 20 years, and both the supply side and the demand side of the industry have experienced a prosperous stage of rapid development. With the fluctuations of the macroeconomic cycle and the impact of unexpected factors such as the novel coronavirus epidemic on all walks of life, the public fund industry has gradually entered a stage of steady development and self-innovation, during which problems in the industry have been exposed. From the national level to the individual level of fund managers, these problems need to be paid close attention to and solved as soon as possible.Among many problems, this paper focuses on the phenomenon of fund managers managing multiple funds. There are a variety of reasons behind this, including a limited pool of talent in the industry and the excessive pursuit of star fund managers by fund companies to attract investors. This paper argues that fund managers‘ concentration is limited, and managing multiple funds may distract their energy, which may lead to poor fund performance even if they have strong enough active management ability. This study can provide some basis for fund companies‘ management and incentive mechanism construction of their internal fund manager teams, and also shows the necessity of rectification and improvement of this phenomenon at the corporate and national levels.Using the relevant data of funds and fund managers from 2003 to 2022, this paper constructs three proxy variables to investigate the concentration of fund managers: The average number of funds, the average external assets, and the proportion of asset scale, among which the latter two are proxy variables at the scale level, supplement the single dimension at the fund quantity level in previous studies, and explore the relationship between fund manager concentration and fund performance under the background that fund managers manage multiple funds. The research results show that limited attention of fund managers will have a negative impact on fund performance, and although this external asset effect is not as significant as the internal fund size effect on fund performance, the two are still in the same order of magnitude, so this external effect deserves attention. In addition, through group regression, it is also found that under different investment strategies, the impact of fund manager‘s concentration on fund performance is different, and active funds are more significantly affected by fund manager‘s concentration. This conclusion will help fund managers and fund companies to better assign tasks and achieve better overall performance, which will have a long-term positive impact on investors, fund companies and the public fund industry.