To determine the appropriate extent to which Italgas S.p.A. should rely on hybrid bonds in its capital structure, we must analyze the company's financial health, 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:** The company has significant long-term financial liabilities. "Long Term Financial Liabilities Excluding Other Non Current Financial Liabilities" increased from ~€5.79 billion in 2022 to ~€6.40 billion in 2023. Total Liabilities are around €8.64 billion against Total Equity of ~€2.39 billion. This results in a Debt-to-Equity ratio of approximately 3.6x, indicating a highly leveraged capital structure.
*   **Interest Coverage:** Profit from Operating Activities (EBIT) for 2022 was ~€641 million. Finance Costs were ~€61 million. The interest coverage ratio is roughly 10.5x, which is healthy. However, the absolute amount of debt is large relative to equity.
*   **Cash Flow:** The company generated positive operating cash flows (~€548 million in 2022), but investing activities consumed significantly more (~€1.28 billion), leading to a negative free cash flow position that was financed through debt and existing cash reserves. Cash and cash equivalents dropped significantly from ~€1.39 billion to ~€452 million.

**2. Cost of Capital and Market Environment:**
*   **Rising Interest Rates:** The swap curves show a dramatic increase in rates from 2021 to 2022. For example, the 10-year swap rate average jumped from 0.053% in 2021 to 1.927% in 2022. The "Bear" case (higher rates) shows rates exceeding 2%. This indicates a rising cost of debt environment.
*   **Credit Spreads:** The iBoxx EUR Non-Financial IG sub-senior delta shows spreads widening or remaining elevated (Average 2.295% in 2022 vs 1.298% in 2021). This suggests that issuing standard senior debt is becoming more expensive.

**3. Role of Hybrid Bonds:**
*   **Equity Credit:** Hybrid bonds are often treated as equity by rating agencies (usually 50-100% equity credit depending on the structure). For a company with a high Debt-to-Equity ratio (3.6x), issuing hybrids can help optimize the leverage ratio without diluting existing shareholders (unlike issuing new shares).
*   **Cost Efficiency:** While hybrids carry a higher coupon than senior debt, they are generally cheaper than equity. In a rising rate environment, locking in long-term capital via hybrids can be strategic, especially if the company needs to de-lever or fund large capex programs (like the €874 million invested in scope changes/consolidation) without further straining senior debt covenants or ratios.
*   **Strategic Fit:** Italgas is a regulated utility with stable cash flows, making it a good candidate for hybrid issuance. Investors accept lower yields on hybrids for such entities due to perceived lower risk of default compared to industrial firms.

**4. Determining the Extent (0%, 25%, 50%, 75%, 100%):**
*   **0%:** Incorrect. The company is highly leveraged and faces rising debt costs. Ignoring hybrid instruments would miss an opportunity to optimize the capital structure and protect credit ratings.
*   **100%:** Incorrect. Relying entirely on hybrids is inefficient due to their higher cost compared to senior debt and tax deductibility issues (interest on senior debt is tax-deductible, hybrid coupons may have different treatments or be higher). A balanced approach is standard.
*   **75%:** Too high. Hybrid bonds are a niche instrument. Most investment-grade utilities maintain a core of senior unsecured debt. A 75% reliance would imply an unusually complex and expensive capital structure.
*   **25% vs 50%:**
    *   Currently, the equity base is ~€2.4bn and senior debt is ~€6.4bn (long term) plus current liabilities.
    *   Introducing hybrids to represent a meaningful portion of the *equity-like* buffer is prudent.
    *   A 50% reliance on hybrids *within the context of new financing or as a portion of total capitalization* is aggressive but potentially justifiable given the high leverage. However, standard corporate finance theory for a stable utility suggests a moderate inclusion.
    *   Let's look at the options as "extent of reliance". Does it mean % of total capital? Or % of *new* issuance? Or % of the *equity/tranche* mix? Usually, these questions refer to the proportion of the capital structure that *should* be composed of such instruments relative to a theoretical optimal mix, or simply a strategic recommendation level.
    *   Given the high leverage (D/E > 3), the company needs equity-like instruments to satisfy rating agencies. However, hybrids are expensive. A balanced capital structure for a utility often includes a small but significant portion of hybrids (e.g., 5-10% of total capitalization).
    *   If the question asks "To what extent... rely on hybrid bonds" among the specific discrete options, we must interpret the scale.
        *   0%: No hybrids.
        *   25%: Moderate reliance (significant part of the capital stack, perhaps replacing some senior debt or equity).
        *   50%: High reliance.
    *   Looking at the peer group for European utilities, hybrid bonds typically make up a small single-digit percentage of total capitalization. However, in the context of *optimizing* a stressed balance sheet (high leverage, dropping cash), increasing the hybrid component is a key lever.
    *   Let's re-evaluate the "Options". These are likely categorical buckets for a strategic stance.
        *   Conservative/Low Leverage: 0-25%
        *   Balanced: 25-50%
        *   Aggressive/High Leverage Optimization: 50%+
    *   Italgas has a D/E of ~3.6. This is high. To improve this without issuing equity, hybrids are the tool. But they are not a panacea.
    *   Let's look at the cost of debt vs equity. With rising rates, senior debt is getting expensive. Hybrids are even more expensive. But equity is the most expensive.
    *   A common strategic allocation for hybrids in the capital structure of European utilities is around 5-15% of total capital. If we map this to the options:
        *   If the options refer to the % of *total capital*, 25% is already very high (most utilities are <10%).
        *   If the options refer to the % of *financial debt* that should be hybrid, 25% is a reasonable target for a highly leveraged firm to gain equity credit.
        *   If the options refer to a subjective "reliance" score, 25% represents a "moderate/strategic" use, whereas 0% is "none" and 50%+ is "heavy".
    *   Given the company's strong operating cash flow but high leverage and falling cash reserves, it needs to preserve financial flexibility. Issuing hybrids allows it to treat the proceeds as equity for rating purposes, lowering the perceived leverage. This is a standard move for companies in this position. It shouldn't be the *primary* source (100% or 75%), nor should it be ignored (0%). Between 25% and 50%, 25% is a more prudent, standard recommendation for the *proportion* of the capital structure or financing mix to be allocated to hybrids to optimize WACC and ratings without overpaying for capital. 50% would be excessively reliant on a high-cost instrument.

    Therefore, a moderate reliance (25%) is the most financially sound advice among the choices, acknowledging the need for equity credit while respecting the cost premium of hybrids.

<answer>25%</answer>