Customer Concentration and Labor Investment Efficiency: Evidence from China

The labor force constitutes a paramount factor of production in the realm of business operations. In the past, China's abundant labor force significantly boosted productivity for firms. However, as the demographic dividend gradually wanes, concerns have arisen regarding a scarcity of labor force, exacerbating worries about rising labor costs. Therefore, focusing on enhancing firms' labor investment efficiency becomes pivotal. Using a sample of A-stock listed firms in China from 2013 to 2020, we examine the impact of customer concentration on the labor investment efficiency of supplier firms. Prior literature provides mixed results regarding the effect of concentrated customers. They can act as a governance mechanism for reducing agency problems, thus, increasing investment efficiency. Conversely, agency problems are aggravated in suppliers with concentrated customers, consequently, reducing investment efficiency. Our results suggest that customer concentration reduces labor investment efficiency, and this effect is more pronounced when customers possess high bargaining power. Additionally, the mechanism analysis reveal that customer concentration leads to less accurate information disclosure, higher operating risk, and an incentive to "empire building", reducing labor investment efficiency. The cross-sectional analysis reveals that customer concentration results in both over- and under-investment in labor, thereby reducing investment efficiency. In addition, we employ augmented models to rule out the possibility of a U-shaped relationship between customer concentration and labor investment efficiency. Furthermore, we adopt the instrumental variables approach as well as a two-stage regression model to address potential endogeneity concerns and mitigate the omitted variable concern. Our results hold after the robustness tests and endogeneity tests. The findings of this paper imply that firms should strategically diversify their customer bases, thereby reducing their reliance on a few large customers. Simultaneously, governments should actively encourage firms to broaden their customer base. It can help enhance labor investment efficiency by spreading the risks associated with customer concentration. Moreover, it is crucial to acknowledge that substantial customer bargaining power can negatively impact supplier firms. Thus, policymakers should promote antitrust regulations and fair trade practices to mitigate the high bargaining power of large customers.