To determine the extent to which ENI S.p.A. should utilize hybrid bonds relative to the S&P Global Ratings cap, we must analyze the company's current capital structure, the cost of capital environment, and the strategic benefits of hybrid instruments.

**1. Analysis of Capital Structure and Current Hybrid Usage:**
From the provided annual report data for 2022 (ending 2023-01-01):
*   **Total Equity:** 55,230 million EUR.
*   **Total Liabilities:** 96,900 million EUR.
*   **Total Assets (Capital Base proxy):** 152,130 million EUR.

S&P Global Ratings typically defines "Adjusted Capital" for the purpose of the hybrid cap as Equity + Debt (including hybrids). The cap states that equity credit granted to hybrids cannot exceed 15% of this total adjusted capital. This effectively limits the amount of hybrid debt a company can issue while still receiving equity treatment.

ENI already has a significant presence in the hybrid market (indicated by "Perpetual Subordinated Bonds" in the equity movement section, with coupon payments noted). The question asks for the *extent* of utilization relative to the cap. This is a strategic question about optimizing the capital structure.

**2. Market Environment and Cost of Capital:**
*   **Interest Rates:** The swap curves show a dramatic increase in rates from 2021 to 2022. The 10Y swap average went from 0.053% in 2021 to 1.927% in 2022. This indicates a rising cost of debt environment.
*   **Credit Spreads:** The iBoxx EUR Non-Financial IG spread increased from 1.298% in 2021 to 2.295% in 2022.
*   **Hybrid Coupon Costs:** Hybrid bonds carry a higher coupon than senior debt due to their subordinated nature and deferrable interest features. However, they offer equity credit (typically 50% or 100% depending on the rating agency's assessment of the instrument's features, but capped in aggregate).

**3. Strategic Rationale for Hybrid Utilization:**
*   **Credit Rating Protection:** ENI is an investment-grade company. Maintaining a strong credit rating is crucial for access to capital markets. Hybrids allow companies to strengthen their leverage ratios (Debt/EBITDA, Debt/Capital) on a rating-agency-adjusted basis because a portion of the hybrid is treated as equity.
*   **Optimizing WACC:** While hybrids are more expensive than senior debt, they are cheaper than pure equity. By utilizing hybrids up to the cap, a company can lower its Weighted Average Cost of Capital (WACC) compared to using only equity, while improving its leverage metrics compared to using only senior debt.
*   **The "Cap" as a Target:** In corporate finance theory for investment-grade issuers with stable cash flows (like ENI, with 17.5 billion EUR operating profit), it is generally optimal to utilize the full allowance of equity-credit instruments provided by rating agencies. This maximizes the financial leverage benefit without triggering a downgrade. The 15% cap is a constraint; efficient capital structure management suggests operating *at* the constraint to maximize the benefit of the cheaper equity-like capital.

**4. Evaluating the Options:**
*   **0%:** Incorrect. ENI already uses hybrids, and they are a standard tool for oil majors to manage leverage.
*   **25%, 50%, 75%:** These represent partial utilization. There is no specific distress signal in the data (high profitability, strong cash flow from operations of 17.46 billion EUR) that would suggest ENI needs to stay well below the cap to preserve rating stability. In fact, with rising interest rates, locking in capital structure efficiency is key.
*   **100%:** This implies utilizing the hybrid instrument allowance to the maximum extent permitted by the rating agency's cap. Given ENI's strong cash generation, investment-grade status, and the typical behavior of major integrated oil companies (which often target the maximum equity credit for hybrids to optimize their gearing ratios), the strategic recommendation is to fully utilize the available headroom under the cap. This allows the company to treat the maximum possible amount of debt as equity for rating purposes, thereby supporting a higher total debt load or a stronger rating for the same debt load.

Therefore, the company should utilize hybrid bonds to the full extent of the cap.

<answer>100%</answer>