创新和创业精神对企业的发展至关重要，特别是在当今快节奏和快速变化的经 济环境中，把握创新即把握未来发展的机遇。民营企业作为市场经济的重要组成部 分，表现出了强大的创造力和生命力，对中国经济的发展起着重要作用，已然成为推 动经济增长和就业创造的重要力量。同时，民营企业创新投入是否能够推动企业的 发展更值得关注。企业创新投入产生的经济结果是多样的，最直观的体现则是在其 市场表现和财务表现之中，企业在股票市场上的股票收益和财务上的绩效收益在一 定程度上体现了其经营成果，同时也能有效体现出创新投入成果。但值得注意的是，由于企业创新行为的复杂性，创新投入产生的经济结果受到市场波动和行业竞争的 影响较大，故传统的股票收益与财务收益指标并不能规避此等影响。考察发现，现有文献主要关注上市公司在股票市场上的超额收益，而对其在经营方面的超额收益研究不足。因此，本文同时考虑上市公司在经营中产生的超额收益以及在股票市场上的超额收益，即相对市场的股票超额收益、财务超额收益，相对行业的股票超额收益、 财务超额收益，将它们作为企业创新投入产生经济结果的衡量指标，研究民营企业创 新投入对超额收益的影响，这在一定程度上减少了市场与行业对于企业创新投入成 果的影响，更加准确地解释了创新投入产生的经济结果。

本文首先对相关文献进行梳理，并对民营企业、创新投入、超额收益做了概念界 定，随之以技术创新理论、风险定价假说、资产错误定价假说、信号传递理论为基础，分析了我国民营企业上市公司创新投入与其超额收益的理论关系。其次，基于相关理 论，分析提出了研究假设。第三，为检验以上假设，本文以 2015-2021 年民营企业上 市公司为样本，以股票超额收益率和净资产超额收益率为被解释变量，用以表示超额 收益；以创新投入强度为解释变量，加入相关控制变量进行基准回归。第四，以上市 板块、创新投入强度以及行业的不同来进行分组回归，解释在不同环境下，各类民营 企业创新投入对其超额收益的影响；与此同时，计算了基于企业规模影响的门槛值。结果表明，民营企业创新投入对其超额收益具有显著正向影响，民营企业创新投入对 其股票超额收益存在门槛效应，民营企业创新投入与超额收益存在倒“U 型”关系。

本文基于公司经营和股票市场上表现的超额收益，研究了民营企业的创新投入对其超额收益的影响，扩展了对民营企业超额收益的研究范围，研究结论具有理论价值和现实意义。

Innovation and entrepreneurship are vital to the development of enterprises, especially in today’s fast-paced and rapidly changing economic environment, where grasping innovation means grasping opportunities for future development.  As an important part of the market economy, private enterprises have demonstrated strong creativity and vitality, and haveplayed an important role in China’s economic development, becoming an important force in driving economic growth and job creation. The ability of private enterprises to invest in innovation to drive their development is of greater concern. The economic results of a company’s investment in innovation are varied and are most intuitively reflected in its market performance and financial performance, with the company’s stock market returns and financial performance gains reflecting its business results to some extent, as well as the results of its investment in innovation.  It is worth noting, however, that due to the complexity of firms’ innovation behaviour, the economic outcomes of innovation inputs are highly influenced by market volatility and industry competition, and therefore traditional stock returns and financial performance indicators cannot circumvent these influences.  It is found that the existing literature focuses on the excess returns of listed companies in the stock market, while the excess returns of their operations are not sufficiently studied. Therefore, this thesis considers both the excess returns generated by listed companies in their operations and in the stock market, i.e. excess stock returns and financial excess returns relative to the market, and excess stock returns and financial excess returns relative to the industry, and uses them as measures of the economic outcomes of corporate innovation inputs to study the impact of private enterprises on excess returns, which to a certain extent reduces the impact of themarket and industry This reduces to some extent the influence of the market and industry on the outcomes of corporate innovation inputs and explains more accurately the economic outcomes generated by innovation inputs.

This thesis firstly compares the relevant literature and defines the concepts of private enterprises, innovation input and excess returns, and then analyses the theoretical relationshipbetween innovation input and excess returns of listed private enterprises in China based on technological innovation theory, risk pricing hypothesis, asset mispricing hypothesis and signaling theory. Secondly, based on the relevant theories, the research hypotheses are proposed in the analysis.  Thirdly, in order to test the above hypotheses, this thesis takes the private enterprise listed companies from 2015-2021 as the sample, and uses stock excess return and net asset excess return as the explanatory variables to represent excess returns; innovation input intensity as the explanatory variables and adds relevant control variables for benchmark regression.  Fourthly, the regressions are grouped by listing sector, innovation investment intensity and industry to explain the impact of innovation investment on the excess returns of various private enterprises in different environments; meanwhile, a threshold value based on the impact of enterprise size is calculated. The results show that private firms’ innovation investment has a significant positive impact on their excess returns, that there is a threshold effect of private firms’ innovation investment on their excess returns, and that there is an inverted ”U-shaped” relationship between private firms’ innovation investment and excess returns.

The thesis also investigates the impact of private enterprises’ innovation investment on their excess returns based on the excess returns of their operations and stock market performance, extending the scope of research on private enterprises’ excess returns.