This paper first introduces the institutional background of the study. In the context of the transition from the approval system to the registration system in China, the gatekeeper role of IPO enterprises has changed from the supervisor to the market, which puts forward higher requirements for intermediary institutions such as securities companies. As an important market medium connecting IPO enterprises and external investors, securities companies are known as the "gatekeepers" of the capital market. They can authenticate and supervise the IPO enterprises they underwrite and/or sponsor. The impact of securities companies on the IPO process has also been a hot topic in the academic and practical circles. This paper examines the impact of internal control of securities companies on IPO companies.This study finds that the higher the level of internal control of securities companies, the higher the quality of IPO companies, including higher IPO information disclosure quality, lower IPO underpricing and higher post IPO performance. The mechanism test indicates that the internal control of securities companies can reduce employees' self-interest behavior and improving employees' work efficiency. Secondly, the impact is stronger in non-state-owned enterprises, when the reputation of securities companies is lower, and the external legal environment is lower. In addition, this study finds the compliance degree of internal control and the reliability of reporting of securities firms are important dimensions that affect the quality of IPO enterprises. iv The conclusions of this study have some practical significance. First, this study finds that the level of internal control of securities firms has an important impact on the quality of IPO enterprises. Therefore, improving the internal control of China's securities companies is an important work that needs to be grasped for a long time. The research conclusions of this paper have important research significance for further optimizing the gatekeeper responsibilities of securities companies and improving the efficiency of resource allocation in the IPO market under the background of the transition from the approval system to the registration system in China's IPO market.

As an alternative to the traditional public transportation system, (urban) rail transit has many advantages such as large capacity, fast speed, tight schedule, safety and comfort, and punctuality, , and has gradually become a top choice of many cities in countering environmental pollution and optimizing traffic quality. At the same time, we must also see that huge amounts of capital are required for the construction of rail transit. The traditional reliance on government investment clearly has its own limitations. The investment not only has a long cost-recovery cycle and a low rate of return, but also hardly attracts investments from the private sector. Therefore, when the government vigorously promotes the construction of a rail transit system, it is generally faced with problems such as a large funding gap and an overall financial loss. Therefore, how to establish a reasonable and efficient mode of investment and financing and further broaden the financing channels for rail transit projects is of great practical significance for improving the profitability of rail transit enterprises and realizing the sustainable development of rail transit. This thesis attempts to study the issue, in general, and further exmines a detailed case study of metro rail transit in a Chinsese city (city A), in particular.

The thesis first studies the concept and attributes of urban rail transit, and analyzes four modes and corresponding cases of urban rail transit investment and financing., It then discusses the characteristics of investment and financing of urban rail transit projects and the concept of investment and financing. Moreover, this thesis focuses on the current situation, characteristics and challenges of city A’s rail transit construction,. More specifically, it takes an in-depth look at the financial planning, investment and financing planning and the investment and financing channels products. The study innovatively puts forward three models, namely, PPP, TOD, ABS of rail transit investment and financing products. Based on the AHP decision-making method, the study shows PPP as the optimal integrated choice for city A. Finally, based on the core issues of the domestic urban rail transit project investment and financing, this thesis analyzes the rationality of the PPP model thoroughly and comes up with some managerial and policy suggestions on how to further optimize the investment and financing of the urban rail transit construction from the perspectives of the government management and the rail transit enterprises