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A New Model of Capital Structure Based on Portfolio Theory
Department of Finance, Ain Shams University, Cairo, Egypt
- 1 Department of Finance, Ain Shams University, Cairo, Egypt
American Journal of Industrial and Business Management·Volume 15 (2025)·Pages 1172–1181·Published 8 August 2025·DOI10.4236/ajibm.2025.158058
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Abstract
In this paper, a theoretical model is introduced to solve for the optimal weights of debt (bonds) and equity (stocks) that determine the minimum weighted average cost of capital (WACC), which in turn leads to maximizing the value of the firm. The model uses a Lagrangian function to determine the optimal weights that minimize risk for a given level of return. The model’s unique contribution is its direct application of the efficient portfolio framework, typically used for investment management, to a firm’s capital components by treating debt and equity as a two-security portfolio. Empirical results of the model using real-world data show the robustness of the model in obtaining the optimal WACC.
KeywordsCapital StructureEfficient MarketEfficient PortfolioOptimal Mix of Debt and EquityMM PropositionsPecking Order TheoryTrade off Theory
- Ahmed, F., Rahman, M. U., Rehman, H. M., Imran, M., Dunay, A., & Hossain, M. B. (2024). Corporate Capital Structure Effects on Corporate Performance Pursuing a Strategy of Innovation in Manufacturing Companies. Heliyon, 10, e24677. https://doi.org/10.1016/j.heliyon.2024.e24677
- Baker, M., & Wurgler, J. (2020). Market Timing and Capital Structure. The Journal of Finance, 57, 1-32. https://doi.org/10.1111/1540-6261.00414
- Brealey, R. A., Myers, S. C., & Allen, F. (2020). Principles of Corporate Finance (13th ed.). McGraw-Hill Education.
- Dang, V. A., Kim, M., & Shin, Y. (2020). Asymmetric Adjustment toward Optimal Capital Structure: Evidence from a Crisis. Journal of Corporate Finance, 60, Article ID: 101541.
- de Prado, M. L. (2016). Building Diversified Portfolios That Outperform Out of Sample. The Journal of Portfolio Management, 42, 59-69. https://doi.org/10.3905/jpm.2016.42.4.059
- DeAngelo, H., & Roll, R. (2015). How Stable Are Corporate Capital Structures? The Journal of Finance, 70, 373-418. https://doi.org/10.1111/jofi.12163
- Fama, E. F., & French, K. R. (1993). Common Risk Factors in the Returns on Stocks and Bonds. Journal of Financial Economics, 33, 3-56. https://doi.org/10.1016/0304-405x(93)90023-5
- Frank, M. Z., & Shen, T. (2016). Investment and the Weighted Average Cost of Capital. Journal of Financial Economics, 119, 300-315. https://doi.org/10.1016/j.jfineco.2015.09.001
- Huang, R., & Ritter, J. R. (2022). Testing Theories of Capital Structure and Estimating the Speed of Adjustment. Journal of Financial and Quantitative Analysis, 57, 1365-1397.
- Jensen, M. C., & Meckling, W. H. (1976). Theory of the Firm: Managerial Behavior, Agency Costs and Ownership Structure. Journal of Financial Economics, 3, 305-360. https://doi.org/10.1016/0304-405x(76)90026-x
- Kraus, A., & Litzenberger, R. H. (1973). A State-Preference Model of Optimal Financial Leverage. The Journal of Finance, 28, 911-922. https://doi.org/10.1111/j.1540-6261.1973.tb01415.x
- Li, X., & Shi, Y. (2021). Capital Structure, Volatility, and Portfolio Optimization: An Integrated Approach. Financial Management, 50, 455-480.
- Mabandla, N. Z., & Marozva, G. (2024). The Effect of Earnings Volatility on Capital Structure: A Case of Oligopolistic Banking Sector. Global Business Review . https://doi.org/10.1177/09721509241301120