نقش اوراق مالی اسلامی (صکوک) دولتی در تأمین مالی زیرساخت‌های پایدار در کشورهای اسلامی: در چارچوب مدل‌سازی پویای پانلی ARDL

1. Introduction and Objective
Sustainable infrastructure financing has become one of the most pressing challenges for governments, particularly in Islamic economies where fiscal constraints, rising public debt, and Sharia-compliance requirements jointly shape public financial management. Infrastructure investment plays a central role in long-term economic growth by enhancing productivity, improving connectivity, and supporting inclusive development. However, financing such investments often requires large-scale, long-term, and stable funding sources that do not impose excessive fiscal burdens.
In this context, sovereign sukuk have emerged as a key Islamic financial instrument capable of mobilizing resources in a Sharia-compliant manner while linking financing to real economic assets. Unlike conventional debt instruments, sukuk are structured around tangible assets and risk-sharing principles, which theoretically enhance financial stability and promote real-sector investment. Over the last two decades, several Islamic countries—including Malaysia, Saudi Arabia, Indonesia, the United Arab Emirates, and Türkiye—have increasingly relied on sovereign sukuk issuance to finance public expenditures and infrastructure projects.
Despite the rapid expansion of the sukuk market, empirical evidence on its macroeconomic effectiveness—particularly in relation to sustainable infrastructure investment—remains limited and fragmented. Existing studies have mainly focused on legal structures, financial performance, or market development, while less attention has been given to its direct impact on productive public investment across countries and over time.
Therefore, the main objective of this study is to empirically investigate the impact of sovereign sukuk issuance on infrastructure investment in selected Islamic countries. Specifically, the study examines whether sovereign sukuk contribute to increasing the ratio of gross fixed capital formation to GDP, while controlling for macroeconomic conditions such as public debt and economic growth. Additionally, the study seeks to distinguish between short-run dynamics and long-run equilibrium relationships, thereby providing a more comprehensive understanding of the role of Islamic sovereign finance in sustainable development.

2. Methodology
This study employs a quantitative econometric framework based on panel data analysis. Annual data from five Islamic countries—Malaysia, Saudi Arabia, Indonesia, the United Arab Emirates, and Türkiye—covering the period 2010–2024 are utilized. The selection of countries is motivated by their active participation in the sovereign sukuk market and the availability of consistent macro-financial data.
The dependent variable is defined as infrastructure investment, measured by the ratio of gross fixed capital formation (GFCF) to GDP. The key independent variable is sovereign sukuk issuance, measured in annual volume (USD billion). In addition, the model includes the public debt-to-GDP ratio as a fiscal constraint indicator, and real GDP growth as a proxy for macroeconomic performance. Interest rate conditions are also incorporated as a control variable to capture financing costs and investment incentives.
To analyze both short-run dynamics and long-run equilibrium relationships, the study employs the Panel Autoregressive Distributed Lag (Panel ARDL) approach using the Pooled Mean Group (PMG) estimator. This method is particularly suitable for heterogeneous panels where short-run coefficients may vary across countries while long-run relationships are assumed to be homogeneous.
Before estimation, panel unit root tests (Levin–Lin–Chu and Im–Pesaran–Shin) are conducted to ensure that variables are not integrated beyond order one. Subsequently, Pedroni’s panel cointegration test is applied to verify the existence of a long-run equilibrium relationship among the variables. Once cointegration is confirmed, the Panel ARDL model is estimated to obtain both long-run coefficients and short-run dynamics.
Finally, diagnostic tests including serial correlation, heteroskedasticity, and normality tests are performed to ensure the robustness and statistical validity of the estimated model. Stability checks across sub-periods are also conducted to verify the consistency of results over time.

3. Research Findings
The empirical results reveal several important findings regarding the relationship between sovereign sukuk issuance and infrastructure investment.

First, the cointegration tests confirm the existence of a stable long-run relationship among the variables, indicating that infrastructure investment, sukuk issuance, public debt, economic growth, and interest rates move together over time in a balanced equilibrium framework.
Second, the long-run estimation results using the PMG estimator show that sovereign sukuk issuance has a positive and statistically significant effect on infrastructure investment. Specifically, increases in sukuk issuance are associated with higher levels of gross fixed capital formation relative to GDP. This finding supports the view that sukuk serve as an effective mechanism for channeling financial resources into productive and development-oriented public investment.
In contrast, the public debt-to-GDP ratio exhibits a statistically significant negative effect on infrastructure investment. This suggests that higher sovereign indebtedness may constrain fiscal space and reduce the government’s ability to allocate resources toward infrastructure development. This result is consistent with the crowding-out effect of public debt in emerging and developing economies.
Economic growth is found to exert a positive and significant influence on infrastructure investment in both the short and long run. This indicates that stronger macroeconomic performance enhances the capacity of governments to invest in infrastructure through higher revenues and improved investor confidence.
Interest rates show a negative relationship with infrastructure investment, reflecting the cost-of-capital channel. Higher real interest rates increase financing costs and therefore reduce investment incentives in infrastructure projects.
The error correction term is negative and statistically significant, confirming the existence of a stable adjustment mechanism toward long-run equilibrium. The magnitude of the coefficient suggests a relatively moderate but steady speed of adjustment, indicating that deviations from equilibrium are corrected over time.
Short-run results further indicate that changes in sovereign sukuk issuance also positively affect infrastructure investment, although the magnitude is smaller compared to the long-run effect. This suggests that sukuk not only support structural development over time but also have immediate stimulative effects on public investment behavior.
Robustness checks across sub-periods confirm that the sign and significance of the main coefficients remain stable over time, reinforcing the reliability of the empirical findings.

4. Conclusion
This study provides empirical evidence on the role of sovereign sukuk in financing sustainable infrastructure investment in selected Islamic countries. Using a Panel ARDL framework over the period 2010–2024, the results demonstrate that sovereign sukuk issuance plays a significant and positive role in enhancing infrastructure investment both in the short run and the long run.
The findings suggest that sovereign sukuk are not merely alternative debt instruments but represent an effective Islamic finance mechanism capable of mobilizing long-term capital for productive public investment. Their asset-backed structure and risk-sharing characteristics make them particularly suitable for infrastructure financing in developing and emerging economies.
At the same time, the results highlight the constraining effect of high public debt levels on infrastructure investment, emphasizing the importance of sustainable fiscal management alongside innovative financing instruments. Macroeconomic stability, reflected in economic growth and interest rate conditions, also plays a critical role in shaping investment outcomes.
From a policy perspective, the results suggest that governments in Islamic countries should further develop sovereign sukuk markets as part of their long-term infrastructure financing strategies. Strengthening institutional frameworks, improving transparency, and expanding investor participation can enhance the effectiveness of sukuk in mobilizing resources for sustainable development.
Overall, the study contributes to the literature by providing cross-country empirical evidence on the macroeconomic impact of sovereign sukuk and highlights their potential as a strategic tool for infrastructure development in Islamic economies.