全面注册制时代，动态调整新股发行规则以改善IPO定价效率对于提升金融服务实体经济质效具有重要意义。科创板、创业板推行注册制后新股发行平稳有序，但也出现了机构投资者重策略轻研究、为博入围抱团报价导致IPO抑价严重的新问题。为解决这一问题，2021年9月18日询价新规正式推行，通过下调高价剔除比例、允许突破“四值孰低”限制对询价机制进行了优化调整，并加强了询价行为的监管和规范。目前关于询价新规政策效果的研究有待补充，深入研究询价新规改革有利于完善询价制度，为全面注册制改革发展提供更多参考。本文围绕询价新规改革，研究询价新规对IPO定价效率的影响及其发挥作用的路径机制，力图准确评估询价新规的政策效应。

首先，基于理论分析和对国内外相关文献的整理，本文提出研究假说。其次，本文以2019至2023年间科创板、创业板注册制新股数据为研究样本，通过连续型双重差分模型研究询价新规对IPO抑价率的影响，并通过中介效应模型研究其机制路径；通过分组回归研究政策影响的异质性；此外进行了询价新规对企业投融资、后市表现影响的拓展研究。为了保证研究的可信性，以替换核心解释变量测度、使用双重纠偏机器学习模型进行稳健性检验，也通过了安慰剂检验。

本文根据实证分析得出结论：（1）询价新规使新股IPO抑价率下降；（2）具体影响路径为：询价新规扩大机构报价的分散度，缓解了机构抱团压价的问题，IPO市场定价效率提高；（3）询价新规对投资者认购热度低（更易出现买方合谋）与企业规模小（信息不对称程度高）的新股影响更显著；（4）询价新规使企业融资与上市后的研发投资更充分，股票的中长期超额收益也显著更高。

根据以上结论，本文提出了加强监管、完善询价定价机制、加强信息披露与利用、呼吁投资者重视价值研究等建议，以推动定价的市场化进程。本文对于更好发挥资本市场枢纽功能以加快建设金融强国，畅通“科技-产业-金融”良性循环、培育新质生产力具有启示意义。

In the era of full registration system, dynamic adjustment of new share issuance rules to improve IPO pricing efficiency is of great significance to enhance the quality of financial services to the real economy. After the registration system was implemented on the Science and Technology innovation Board and the Growth Enterprise Board, the issuance of new shares was stable and orderly, but there was also a new problem that institutional investors attached importance to the quotation strategy and jointly depressed the quotation, resulting in serious underpricing of IPO. The new rules on inquiry were officially implemented on September 18, 2021, which optimized and adjusted the inquiry mechanism by lowering the proportion of high price exclusion and allowing the breakthrough of the "four values which is lower" limit, and strengthened the supervision and regulation of inquiry behavior. At present, the research on the effect of the new regulation policy needs to be supplemented, and in-depth research on the reform of the new regulation is conducive to improving the inquiry system and providing more references for the reform and development of the comprehensive registration system. This paper focuses on the reform of the new rules of inquiry, studies the influence of the new rules of inquiry on IPO pricing efficiency and its mechanism, and tries to accurately evaluate the policy effect of the new rules of inquiry.

Firstly, based on the collation and theoretical analysis of relevant literature, we propose a corresponding research hypothesis. Secondly, this paper takes the data of registered new shares on the Science and Technology Innovation Board and Growth Enterprise Board from 2019 to 2023 as research samples. The impact of the new regulations on the underpricing rate is studied through the continuous difference-in-difference model, and the mechanism path is studied through the mediation effect model. The heterogeneity of the impact of the new policy on inquiry was studied through group regression; In addition, the impact of the new rules on inquiry's investment and financing and market outlook performance was also tested. In order to ensure the credibility of the study, the robustness test was conducted by replacing the core explanatory variable measure and using DDML model, which also passed the placebo test.

According to the research, we have the following conclusions: (1) The new rules on inquiry have reduced the underpricing rate of new stock IPOs. (2) The new rules on inquiry have expanded the dispersion of institutional quotations, alleviated the problem of agencies jointly deliberately underbidding, and improved the pricing efficiency of the market. (3) The new rules have a more significant impact on new shares with low investor enthusiasm (more likely to appear buyer collusion) and small enterprise size (high degree of information asymmetry). (4) The new regulations make the financing of enterprises in the listing and the research and development investment after the listing more adequate, and the medium and long-term excess returns of stocks are significantly higher.

According to the above conclusions, this paper puts forward some suggestions, such as strengthening supervision, improving inquiry pricing mechanism, strengthening information disclosure and utilization, and calling on investors to pay attention to value research, so as to promote the marketization process of pricing. This paper has enlightenment significance for better play the hub function of capital market to speed up the construction of financial power, smooth the virtuous cycle of "science and technology - industry - finance" and cultivate new quality productivity.