Based on the financial data provided for Hera S.p.A., here is the reasoning for determining the appropriate reliance on hybrid bonds.

**1. Assessing Financial Health and Earnings Stability**

*   **Revenue:** Revenue almost doubled from €10.56 billion (2021) to €20.08 billion (2022), and other revenue also increased significantly. This indicates substantial business growth, likely driven by the energy sector's price volatility.
*   **Operating Profit:** Despite the revenue surge, operating profit decreased from €611.7 million to €533.8 million. This suggests the increased revenue came with disproportionately higher costs (raw materials surged from €6.67B to €16.73B), compressing margins.
*   **Profitability:** Net profit attributable to owners decreased from €333.5 million to €255.2 million. Basic EPS fell from €0.228 to €0.175.
*   **Cash Flow Volatility:** Operating cash flow collapsed from €1,045.4 million (2021) to only €35.7 million (2022). This dramatic decline was due to a massive increase in working capital (a cash outflow of €927.6 million vs. an inflow of €47.8 million in 2021), driven by a surge in inventories (€627.4M outflow) and trade receivables (€1,280.7M outflow), which were not fully offset by higher payables. This signals a significant liquidity strain in 2022 despite higher nominal revenues.

**2. Analyzing Capital Structure and Leverage**

*   **Equity:** Total equity is €3,644.7 million, representing 21.3% of total assets (€17,118.5 million). This is a relatively solid equity base, though down from 24.3% in 2021, indicating increased leverage.
*   **Debt:** Non-current financial liabilities jumped from €3,716 million to €5,689.9 million. Total non-current liabilities are €6,624.6 million.
*   **Coverage:** The operating profit of €533.8 million does not appear robust relative to the growing debt pile, especially considering the finance costs of €217.2 million (up from €300.3M? No, the raw data shows "Finance Costs" 2021: -300.3M, 2022: -217.2M. Wait, let me re-read: "Finance Costs" 2022: 217200000 EUR, "Finance Costs" 2021: 300300000 EUR. Finance costs *decreased* from 300.3M to 217.2M. However, the "Finance Income Cost" net was -125M in 2022 vs -204.8M in 2021).
*   **Hybrid Bond Suitability:** Hybrid bonds are an attractive tool for companies needing to strengthen their balance sheet without increasing net debt. They receive partial equity treatment (usually 50%) from rating agencies like S&P and Moody's. Given Hera's sharp increase in leverage, volatile cash flow generation, and compressed interest coverage (EBIT/Finance Costs = 533.8/217.2 ≈ 2.46x), a modest injection of hybrid capital would be beneficial. It would support the credit rating by bolstering the equity cushion against the large working capital-driven debt swings seen in 2022. However, excessive reliance (75-100%) could be costly and signal distress. 0% means missing an opportunity to optimize the cost of capital and protect the balance sheet. A moderate 25% slice represents a prudent, strategic use for a utility-like business with volatile operating cash flows but a stable long-term asset base.

**Conclusion:** A 25% reliance on hybrid bonds would provide balance sheet flexibility without over-reliance on an expensive instrument, fitting the profile of a capital-intensive business experiencing temporary cash flow pressures due to commodity price cycles.

<answer>25%</answer>