险资股权投资的结构性改革研究*——基于险资投资的倒U型效应分析

保险资金作为重要的机构投资者能否发挥促进公司绩效提升的作用在已有研究和监管政策制定上都存在较大争议。本文以2005-2017年A股上市公司为研究样本，发现险资持股比例对上市公司绩效以及估值影响存在显著的倒U型曲线效应，相应机制研究表明险资持股通过显著影响两类代理成本的渠道发挥治理作用。在适度持股比例以下，险资增持能够降低被投资公司管理费用率和其他应收款占比，并提高资产周转率，从而降低两类代理成本；持股超过一定比例反而造成两类代理成本上升。险资持股比例变化对保险机构调研次数的影响则从公司治理参与角度印证了以上结论。对倒U型曲线效应的深入分析既有助于深化对机构投资者影响公司绩效的多重效应和机制的认识，同时为在金融机构层面落实金融供给侧结构性改革、增强险资服务实体经济能力提供参考。

INSURANCE FUNDS' EQUITY INVESTING NEEDS A STRUCTURAL REFORM——An Analysis Based on the Inverted U shaped Curve Effect

As an important institutional investor, whether insurance funds can play an important role in promoting corporate performance is controversial in the existing research and regulatory policy formulation. Based on the sample of A share listed companies from 2005 to 2017, this paper finds that there is a significant inverted U shaped curve effect on the performance and valuation of listed companies in China. And this paper finds this inverted U shaped effect is mainly caused by reducing type I and type II agency costs. As the shareholding of insurance fund raises under the threshold, the type I and type II agency cost goes down accordingly, but goes up if it is above the threshold. The evidence that changes in insurance funds’ shareholdings influence the frequency of corporate site visits sponsored by insurance institutions further reinforces the above conclusions from the perspective of corporate governance participation. The empirical evidences help us understand the multiple effects and mechanisms between institutional investors and corporate performance. And it is also possible to provide reference for the formulation of a more consistent supervision policy about insurance fund's equity investment.