To assess the appropriate level of hybrid bond issuance for Acciona SA, we analyze its financial position as of December 31, 2022.

**Financial Analysis:**
1.  **Capital Structure:** The company's total equity is 6,304 million EUR. Total debt includes non-current loans (2,624 million EUR), current loans (553 million EUR), and other significant financial instruments/securities ("Participaciones Preferentes, Obligaciones y Otros Valores Negociables," totaling 3,101 million EUR non-current and 1,139 million EUR current).
2.  **Growth and Capex:** Acciona is in a high-growth phase, particularly in renewable energy. Property, Plant, and Equipment grew from 8,066 million EUR to 9,485 million EUR (an increase of over 1.4 billion EUR). Investing activities show a significant cash outflow of 1,944 million EUR, driven largely by capital expenditures (2,195 million EUR).
3.  **Leverage and Ratios:** While operating cash flow is strong (1,648 million EUR), the company's aggressive expansion strategy results in significant financing needs. The "Participaciones Preferentes" (hybrids) already represent a substantial portion of the capital structure (4.24 billion EUR total).
4.  **Rationale:** The company is maintaining a high rate of investment. Given the capital-intensive nature of its renewable energy projects, it requires ongoing access to capital markets. Using hybrids allows Acciona to manage its adjusted leverage ratios while supporting its significant capital investment programs, which are essential for maintaining its competitive position and long-term credit profile in a rising interest rate environment (as evidenced by the 2022 swap curves).

**Assessment:**
The company’s capital-intensive strategy and the need to preserve an investment-grade credit profile while managing a substantial investment pipeline point toward the need for leverage optimization. A 7.5% allocation fits the requirement for moderate refinancing/acquisition support and meaningful leverage improvement, balancing the cost of debt with the need for financial flexibility.

<answer>7.5%</answer>