Emerging transportation infrastructure (e.g., HSR) is considered to be an important influencing factor of executive compensation in China. Moreover, information asymmetry is a contextual factor that cannot be ignored in the above relationship. The operation of HSR positively affects the executive compensation of enterprises in cities along the line. In addition, compared with state-owned enterprises, the impact of a high-speed railway on executive compensation is particularly significant in private enterprises. Furthermore, compared with well-known enterprises, the impact of high-speed railways on executive compensation is particularly significant in enterprises with low visibility.
In recent years, executive compensation has become one of the most controversial issues in corporate governance and has attracted extensive attention from scholars 
. At present, China’s labor market has changed from an equal central planning system to a complex market system, and market characteristics will have an impact on labor compensation that cannot be ignored 
. For example, due to the high mobility of senior executives, the market cluster effect of urban agglomeration significantly influences the standard and structure of executive salaries 
. To absorb the benefits of network spillovers and large-scale markets in urban agglomerations, enterprises are often willing to pay a premium, which leads to a positive correlation between urban agglomerations and executive compensation 
. Therefore, it is worth discussing the impact that transportation infrastructure will bring to executive compensation in the context of the urban agglomeration phenomenon.
As an emerging type of transportation infrastructure, high-speed railways are an important strategic initiative to connect marginal cities, promote information dissemination, drive the regional economy, and improve industrial agglomeration 
. In terms of geographical connections, high-speed railways ameliorate transportation facilities and improve accessibility between cities, especially the long-distance connections of marginal cities 
. Regarding information transmission, high-speed railways enhance communication closeness among economic entities, resulting in a knowledge spillover effect 
. With respect to the economy, high-speed railways can bring more entrepreneurial opportunities for cities, as well as attracting abundant talent, and can indirectly stimulate economic growth. In the field of industrial agglomeration, high-speed railways transfer labor and production factors from small cities to large cities, thus enhancing the degree of specialization and the industrial agglomeration effect 
Most of the existing literature on the influencing mechanism of high-speed railways is focused on the perspectives of the economy, trade, and population mobility. Generally, scholars have two different views. On the one hand, scholars believe that the impact of high-speed railways on the urban economy is positive. HSR can promote the economic growth of cities along the line by increasing the mobility of the labor force, trade contacts, and the speed of information dissemination 
. For example, Cascetta et al. 
showed that HSR in Italy contributed to an extra growth of per capita GDP of +2.6% in 10 years. On the other hand, scholars have suggested that the impact of HSR on the urban economy is negative. High-speed railways not only increase the cost of resource transportation but also make a large number of resources flow into the core cities, which may cause the unbalanced development of the regional economy and form a “metropolitan effect” 
. However, the current research is less involved with the impact of HSR on the executive compensation of listed companies in cities along the line. As an important incentive factor to improve the work enthusiasm of senior executives, compensation determines whether enterprises can attract and retain talent to achieve sustainable development 
. Therefore, the relationship between high-speed railway operation and executive compensation is a significant research topic that affects the survival and development of enterprises.
In addition, ownership and management rights are separated in modern enterprises. Shareholders must entrust managers to operate to maximize the value of companies. Due to people’s self-interest, executives may sometimes damage the benefits of shareholders for their own profits, resulting in contradictions with shareholders. The contradiction of this principal–agent model is rooted in the information asymmetry between shareholders and managers. Information asymmetry reflects the size of the gap between the information held by both sides of the relationship. This phenomenon is particularly serious in lower-profile private firms and enterprises because these enterprises are usually not required to disclose vast quantities of important information 
. A higher degree of information asymmetry indicates that there exists an obvious disparity in the amount of information held by both players in the relationship, which means that the enterprise’s information management system is not perfect. A lower degree of information asymmetry indicates that both sides of the relationship have the same amount of information, which means that the information transparency of the enterprise is higher. Thus, due to the different degrees of information asymmetry, it is worth examining whether the effect of high-speed railways on executive compensation shows diverse results among various types of enterprises.
2. Relationship between Chinese Executive Compensation and High-Speed Railways
Scholars have proven the “metropolitan effect” of HSRs as an emerging type of transportation infrastructure 
. It is worth discussing whether high-speed railway operation has an effect on compensation, as the most attractive factor in a city. Therefore, herein regarded the operation of HSRs as an exogenous shock, using the time-varying DID method to verify the relationship between HSR operation and executive compensation based on information asymmetry theory. Herein arrived at the following three conclusions.
First, HSR operation has a significantly positive influence on executive compensation. Second, the positive relationship between HSRs and executive compensation is stronger in private firms. Third, the positive relationship between HSR and executive compensation is stronger in low-visibility firms. Previous studies have studied the effect of HSR operation on environmental pollution 
and corporate social responsibility 
based on the social pressure perspective. Several studies, for example, that of Jin et al. 
, from the information asymmetry perspective, have studied the HSR effect on firms’ cross-region merger and acquisitions and obtained the conclusion that HSRs can reduce the degree of distance-induced information asymmetry between bidders and targets by reducing travel time and cost. The research results provide support for the viewpoint of the present study that the opening of high-speed railways reduces information asymmetry.
First, the relationship between HSR and executive compensation shows that HSR operation has a significant role in promoting executive compensation. This indicates that the opening of HSRs can increase information access channels for the Board of Directors and shareholders so that they can more accurately understand the actual ability of senior executives and pay them higher salaries to avoid job vacancies. In addition, high-speed railways can also provide more employment opportunities for executives and enable them to find jobs with higher compensation in other cities along the line, which is supported by Willigers 
. Therefore, after the opening of HSR, the Board of Directors and shareholders of enterprises in cities along the railway should take some measures to standardize the salary system. On the one hand, the Board of Directors can make use of the accessibility of high-speed railways to strengthen the close relationships with other economic entities, broaden the business scope of enterprises, and learn from new innovation models to improve the business performance of enterprises and then improve the overall level of executive compensation 
. On the other hand, with the help of convenient information dissemination channels, the Board of Directors can learn more information related to the actual ability of executives, so it can understand the contribution of executives correctly and improve the remuneration of executives within a certain range.
Second, it is concluded that compared with state-owned enterprises, the promoting effect of high-speed railways on executive compensation is more significant in private enterprises. This conclusion is consistent with the study of Dai and Cheng 
, who showed that state-owned firms suffer less information asymmetry than non-SOEs. This indicates that due to the different degrees of information asymmetry between state-owned and private enterprises, the impact of high-speed railways on executive compensation presents discrepant results. Specifically, in private enterprises, the problem of information asymmetry is more serious, so the opening of high-speed railways is conducive to improving the information transmission mechanisms of enterprises, which allows the Board of Directors to make a more objective evaluation of the actual working ability of executives. At the same time, to avoid the risk of brain drain, the Board of Directors will pay the top managers a higher salary. Therefore, after the opening of high-speed railways, the Board of Directors and shareholders in private enterprises should take the initiative to improve the management system and information transmission mechanism of enterprises, increase the communication frequency with executives, and learn more information that can reflect their actual value. These measures can provide a more reliable basis for improving executive compensation. At the same time, improving executive compensation is also an important strategy to reduce the risk of brain drain, which can ensure that the company will not face the dilemma of job vacancies and will operate normally.
Third, herein found that compared with well-known enterprises, the promotional effect of high-speed railways on executive compensation is more significant in low-profile enterprises. This implies that enterprises with low popularity also have serious information asymmetry problems. The opening of high-speed railways increases the attention of enterprises, which results in enterprises disclosing more information related to enterprise value for positive evaluation and using the obtained resources to improve the efficiency of resource allocation. These measures can contribute to the development of enterprises and improve executive compensation. Therefore, if low-profile enterprises are located in cities along high-speed railways, they should establish a self-restraint mechanism and improve the internal salary management system first. Then, by taking advantage of the accessibility and knowledge spillover effect of high-speed railways, they can build a social network with higher embeddedness to share information and collect resources, which can help enterprises obtain more social recognition and enhance their competitive advantages.