To determine the appropriate extent to which Hera S.p.A. should rely on hybrid bonds in its capital structure, we must analyze the company's financial health, risk profile, cost of capital environment, and strategic needs based on the provided 2022 annual report data and market conditions.

**1. Financial Health and Leverage Analysis**
*   **Debt Levels:** Hera has significant liabilities. Total Liabilities in 2022 were €13.47 billion, while Equity was €3.64 billion. This results in a Debt-to-Equity ratio of approximately 3.7x. The Noncurrent Financial Liabilities increased significantly from €3.72 billion in 2021 to €5.69 billion in 2022, indicating a recent aggressive borrowing strategy or refinancing activity.
*   **Interest Coverage:** The Profit from Operating Activities (EBIT) was €533.8 million. Finance Costs were €217.2 million. The interest coverage ratio is roughly 2.45x ($533.8 / 217.2$). While positive, this is not exceptionally high, suggesting that adding more debt with mandatory interest payments could strain cash flows, especially if rates rise further.
*   **Cash Flow:** Operating Cash Flow was very low at €35.7 million in 2022, a drastic drop from €1.04 billion in 2021. This was largely due to working capital changes (increase in receivables and inventories). However, Financing Cash Flow was strongly positive (€1.78 billion), driven by €2.12 billion in proceeds from non-current borrowings. This indicates the company is currently reliant on debt markets to fund operations and investments.

**2. Cost of Capital and Market Environment**
*   **Rising Interest Rates:** The swap curves show a dramatic shift from negative/low rates in 2020-2021 to positive, higher rates in 2022 (e.g., 10Y Swap Average moved from 0.053% in 2021 to 1.927% in 2022). The iShares Core Euro Corp Bond yield also rose to 1.085%. This increases the cost of traditional debt.
*   **Hybrid Bond Appeal:** Hybrid bonds (subordinated debt with equity-like features) typically offer higher yields than senior debt but lower than equity. In a rising rate environment, locking in long-term capital via hybrids can be attractive if they are treated as equity for rating agency purposes. This helps maintain credit ratings despite high nominal leverage.

**3. Strategic Fit for Hybrids**
*   **Equity Treatment:** Hybrids are often used by utilities like Hera to optimize the capital structure. They count as equity for regulatory and rating purposes (de-leveraging the balance sheet visually) but provide tax-deductible interest payments (unlike dividends).
*   **Rating Agency Pressure:** With a Debt/Equity ratio of ~3.7x, Hera is highly leveraged. To maintain an investment-grade rating (crucial for a utility to keep borrowing costs manageable), it needs to bolster its equity base. Issuing pure equity dilutes existing shareholders and might be expensive if the stock price is not favorable (EPS dropped from 0.228 to 0.175). Issuing more senior debt worsens the leverage ratios. Hybrids offer a middle ground.
*   **Dividend Policy:** Hera pays significant dividends (€174.7 million to parent owners). Hybrids allow for deferral of coupons under certain conditions, providing flexibility compared to senior debt, which aligns with the utility's need for stable but flexible cash management.

**4. Evaluating the Options**
*   **0%:** Relying solely on senior debt and equity is suboptimal given the high leverage. Adding more senior debt increases financial risk and interest burden. Issuing more equity is dilutive.
*   **100%:** Relying entirely on hybrids is impractical. Hybrids are expensive compared to senior debt and complex. Senior debt is still the cheapest source of funding for a stable utility. A 100% hybrid structure would drastically increase the weighted average cost of capital (WACC).
*   **75%:** This is too high. Hybrids are a niche instrument. A structure dominated by hybrids would signal distress or an overly aggressive optimization strategy that rating agencies might look through, treating them as debt anyway if the volume is too high relative to true equity.
*   **50%:** This is a very aggressive target. While hybrids are useful, having half the capital structure (or half the debt-like instruments) as hybrids is unusual for a standard utility unless it is undergoing a major restructuring. It introduces significant complexity and cost.
*   **25%:** This is the most balanced and standard approach for a large European utility with high leverage. It allows Hera to:
    1.  Strengthen its equity ratio for rating agencies (treating hybrids as equity).
    2.  Diversify its funding sources.
    3.  Avoid the full dilution of equity issuance.
    4.  Keep the majority of its debt in cheaper senior instruments.
    5.  Manage the interest coverage ratio by deferring coupons if necessary (though unlikely for a stable utility).

Given Hera's specific situation—high leverage, rising interest costs, and the need to protect its investment-grade rating while funding capital-intensive infrastructure—a moderate inclusion of hybrid bonds is optimal. It acts as a buffer between senior debt and equity. A 25% allocation of the *debt-like* or *total capital* structure (depending on interpretation, but generally meaning a significant but not dominant portion of the financing mix) is a standard best practice for such entities to optimize WACC and ratings. In the context of the options provided, 25% represents a strategic, prudent use of hybrids to supplement equity without over-relying on their higher cost.

<answer>25%</answer>