How Does Supply Chain Finance Affect Intra-firm Income Inequality? Evidence from Market Power and Skill Premiums in China

Technical Summary: Supply Chain Finance and Intra-firm Income Inequality in China

Problem Statement
Global income inequality remains a critical policy challenge, with intra-firm wage disparities accounting for a significant portion of overall societal income dispersion, particularly in post-reform China. While financial development is recognized as a driver of economic growth, its distributional consequences are complex. This paper investigates a specific, under-explored mechanism: how Supply Chain Finance (SCF)—a financing model leveraging the creditworthiness of core firms to support upstream and downstream Small and Medium-sized Enterprises (SMEs)—affects intra-firm income inequality. The central research question is whether SCF, despite its ability to alleviate financing frictions and boost liquidity, inadvertently reshapes the functional distribution of income within core firms, potentially exacerbating pay gaps between executives, high-skilled workers, and low-skilled labor.

Methodology
The study employs a quantitative empirical approach using a panel dataset of A-share listed firms in China from 2009 to 2022.

• Data Sources: Data is drawn from the CSMAR and Wind databases.
• Key Variables:
  • Independent Variable: SCF engagement is identified via a two-step process involving keyword searches in corporate announcements and textual analysis of annual reports to create a dummy variable ($SCF$).
  • Dependent Variable: Intra-firm income inequality ($Lwgap$) is measured as the natural logarithm of the ratio between average executive compensation and average ordinary employee compensation.
  • Controls: Firm-level characteristics (size, age, leverage, ROE, TFP), industry concentration, and macroeconomic factors.
• Econometric Strategy:
  • Baseline Estimation: Fixed-effects panel regressions with firm and year fixed effects.
  • Robustness Checks: The authors conduct extensive robustness tests, including replacing dependent and independent variables, winsorizing controls, excluding megacities, adding high-dimensional fixed effects, and controlling for digital financial inclusion.
  • Endogeneity Mitigation: The study utilizes a Two-Stage Least Squares (2SLS) approach using provincial/municipal government SCF support policies as an instrumental variable. Additionally, Propensity Score Matching (PSM) is used to address self-selection bias, and a Difference-in-Differences (DID) event-study design is employed around the 2017 national SCF policy implementation to verify parallel trends and dynamic effects.
  • Mechanism Analysis: The paper tests four transmission channels: market power (markup and superstar effects), digital-biased technological progress, labor income share, and skill premiums.
  • Theoretical Framework: A simple theoretical model based on a nested CES production function with capital-skill complementarity and monopolistic competition is used to derive comparative statics linking SCF-induced changes in markups and technology parameters to labor shares and wage gaps.

Key Contributions
The paper makes four distinct contributions to the literature:

1. Causal Link: It establishes a causal relationship between SCF and intra-firm income inequality, extending the distributional analysis of financial innovations beyond traditional credit markets.
2. Focus on Core Firms: Unlike prior studies focusing on SMEs, this research centers on core firms, delineating how their enhanced market power and resource control drive inequality.
3. Transmission Channels: It identifies and empirically validates four specific mechanisms: (i) the consolidation of market power shifting rents to capital; (ii) digital-biased technological change displacing low-skilled labor; (iii) the compression of the aggregate labor income share; and (iv) the amplification of skill and managerial rent-seeking premiums.
4. Labor Supply Elasticity: It investigates the asymmetric effects of SCF on the labor supply elasticity of high-skilled versus low-skilled workers, revealing structural imbalances in the labor market.

Empirical Results
The baseline results and robustness checks yield four primary findings:

1. Employment vs. Inequality Trade-off: SCF significantly expands total employment within core firms but simultaneously reduces the labor income share and worsens internal pay inequality. The coefficient for SCF on income inequality is positive and significant (approx. 0.213).
2. Mechanism Validation:
   • Market Power: SCF increases firm markups and "superstar" market effects, allowing core firms to extract rents that are allocated to capital and executives rather than labor.
   • Skill-Biased Tech: SCF drives digital transformation (measured by patent output and digital adoption), which increases the demand for high-skilled labor while displacing low-skilled workers, widening the skill premium.
   • Managerial Rent-Seeking: Enhanced market power facilitates excessive executive compensation, widening the gap between top management and rank-and-file employees.
3. Heterogeneity: The inequality-widening effect is more pronounced in:
   • Firms with high horizontal monopoly power (high Lerner index).
   • Firms with high supply chain resilience (strong vertical lock-in).
   • Firms with concentrated executive shareholding and financially literate executives.
   • Labor-intensive and low-skill-concentrated firms, where factor misallocation is more severe.
4. Labor Supply Asymmetry: Under SCF, the supply elasticity of unskilled labor decreases significantly, while the supply elasticity of skilled labor remains unchanged. This creates a structural imbalance where low-skilled workers face falling wages and excess supply, while high-skilled workers command rising premiums despite a relative shortage, further entrenching inequality.

Significance and Policy Implications
The paper argues that while SCF is a vital financial innovation for stabilizing supply chains and alleviating financing constraints for SMEs, it carries significant distributional risks. The "lock-in" effect of SCF consolidates the bargaining power of core firms, leading to a redistribution of economic rents away from labor and toward capital and high-skilled elites.

The authors propose three targeted policy interventions to mitigate these effects without stifling financial innovation:

1. Regulatory Reform: Standardize SCF market conduct to prevent core firms from abusing dominance. Regulators should encourage credit assessment based on physical collateral and digital data rather than over-reliance on core firm confirmations, and establish cross-departmental monitoring platforms.
2. Compensation Governance: Implement rational compensation frameworks to curb managerial rent-seeking. This includes strengthening the independence of remuneration committees, linking executive pay to long-term ESG and risk-adjusted metrics rather than short-term stock performance, and potentially imposing progressive surtaxes on excessive executive pay.
3. Factor Allocation and Skill Upgrading: Address the structural labor imbalance by expanding the supply of skilled labor. This involves coordinated vocational training systems linking universities, enterprises, and social institutions to upgrade low-skilled workers, thereby reducing the skill premium gap and improving the bargaining power of the broader workforce.

In conclusion, the paper posits that achieving Inclusive Growth requires not only the expansion of financial tools like SCF but also the calibration of regulatory policies to ensure that the efficiency gains from supply chain integration are shared more equitably across the workforce.