To evaluate the extent to which Acea S.P.A. should rely on hybrid bonds, we examine its financial position and market context as of the end of 2022:

1.  **Capital Structure & Financial Health:** Acea exhibits a robust equity base (approx. €2.76 billion) and substantial total assets (€11.34 billion). The profit attributable to owners of the parent remained strong at €279.7 million in 2022, despite the economic environment.
2.  **Cost of Debt and Market Environment:** The market data (Swap Curves 5Y, 7Y, 10Y) shows a significant increase in interest rate benchmarks from 2021 to 2022 (e.g., 10Y swap rising from 0.053% to 1.927%). Furthermore, the iBoxx EUR Non-Financial IG spread (Sub-Sen Delta adjusted) increased from 1.298% in 2021 to 2.295% in 2022. This environment indicates that traditional debt issuance has become significantly more expensive.
3.  **Hybrid Bond Considerations:** Hybrid bonds offer a balance between equity and debt. While they provide tax-deductible interest payments (attractive in a high-rate environment), they are more expensive than senior debt and dilute the credit profile slightly less than equity. Given Acea’s status as an Italian utility company with stable, regulated cash flows, it can manage the higher coupon associated with hybrids without risking its investment-grade status.
4.  **Strategic Balance:** A 25% reliance on hybrid instruments within the capital structure allows the company to diversify its funding sources, optimize the cost of capital by leveraging the tax shield of hybrid coupons, and maintain financial flexibility for ongoing investments in intangibles and property, plant, and equipment (which increased from €2.94B to €3.14B in 2022). A higher percentage might be overly aggressive given the potential for volatility in utility-sector spreads, while a lower percentage underutilizes potential capital optimization in the current rate environment.

<answer>25%</answer>