To determine the extent to which Red Eléctrica Corporación, S.A. (REDEIA) should utilize hybrid bonds relative to S&P Global Ratings' cap, we must analyze the company's current capital structure, credit profile, and the strategic implications of issuing hybrid debt.

**1. Analysis of Current Capital Structure (as of 2023-01-01):**
*   **Total Equity:** 4,894,276,000 EUR
*   **Total Liabilities:**
    *   Noncurrent Liabilities: 6,984,202,000 EUR
    *   Current Liabilities: 2,903,042,000 EUR
    *   Total Liabilities = 9,887,244,000 EUR
*   **Total Debt (Financial Liabilities):**
    *   Noncurrent Financial Liabilities: 5,543,755,000 EUR
    *   Current Financial Liabilities: 1,705,277,000 EUR
    *   Total Debt = 7,249,032,000 EUR
*   **Total Adjusted Capital (Debt + Equity):**
    *   Using the definition provided (Debt + Equity): 7,249,032,000 + 4,894,276,000 = 12,143,308,000 EUR.
    *   *Note: S&P often uses Total Capitalization (Debt + Equity). Let's stick to the prompt's definition.*

**2. S&P Global Ratings Methodology for Hybrids:**
*   S&P typically grants **50% equity credit** to hybrid instruments that meet specific criteria (subordination, deferral clauses, etc.).
*   The prompt states a cap where equity credit on hybrids is limited to a maximum of **15% of total adjusted capital**.
*   This implies that the company can issue hybrids such that the *equity credit portion* does not exceed 15% of the total capital base. Since the equity credit is usually 50% of the hybrid's face value, the company could theoretically have hybrids amounting to 30% of total capital (50% of 30% = 15% equity credit). However, the question asks for the utilization *relative to the cap*.

**3. Strategic Assessment of REDEIA:**
*   **Credit Rating Profile:** Red Eléctrica is a regulated utility with stable cash flows, typically holding an investment-grade rating (often A-range). Regulated utilities benefit significantly from maintaining strong investment-grade ratings to keep borrowing costs low.
*   **Interest Rate Environment:** The market data shows a sharp increase in swap rates and bond yields in 2022 (e.g., 10Y Swap average rose from -0.143% in 2020 to 1.927% in 2022). Issuing new debt, including hybrids, has become more expensive.
*   **Leverage:** The company's Debt-to-Equity ratio is approximately 1.48 (7.25B / 4.89B). This is a moderate leverage level for a utility.
*   **Equity Strength:** The company has a robust equity base (4.89B EUR) and generated significant comprehensive income (790M EUR) in the period. The "Fondos Propios" (Equity) increased from 3.76B to 4.82B, showing strong internal capital generation.
*   **Need for Hybrid Capital:** Hybrid bonds are typically used to optimize the capital structure by lowering reported leverage (since they count partially as equity) without diluting shareholders. However, they carry a higher coupon than senior debt. Given the rising interest rate environment (high cost of hybrids) and the company's already solid equity position and investment-grade status, there is limited urgent need to aggressively push against the regulatory/rating agency cap to save equity credit.
*   **Rating Agency Constraints:** S&P caps the equity credit to prevent companies from artificially inflating their equity base. For a stable, regulated utility like REDEIA, maintaining a conservative approach is standard. They do not need to maximize the hybrid allowance to support their rating, as their operational cash flows are sufficient. Over-utilization (75% or 100% of the cap) would introduce unnecessary cost and complexity. Under-utilization (0%) might miss out on some optimization, but 25% or 50% represents a balanced approach.
*   **Standard Practice:** Most European utilities with strong ratings utilize hybrids moderately to fine-tune leverage ratios. They rarely max out the cap because the marginal benefit of additional equity credit diminishes while the cost of capital (coupon) remains high. A utilization of **50%** of the available cap is a common strategic target for such entities to maintain flexibility and optimize the weighted average cost of capital (WACC) without over-leveraging with expensive hybrid instruments. It allows for some leverage optimization while retaining headroom for future needs or market volatility.

However, looking closer at the specific phrasing "relative to S&P Global Ratings' cap", and considering the high cost of debt in 2022 (Swap curves up significantly), the incentive to issue *new* hybrids is low. But the question asks about the extent they *should* utilize. Given the strong balance sheet, they are not *forced* to use hybrids. But to optimize capital structure efficiently, a moderate usage is typical.

Let's re-evaluate based on the "Cap" concept. If the cap is 15% of total capital as *equity credit*, and hybrids get 50% credit, the max hybrid debt is 30% of capital.
Current Debt/Total Capital = 7.25 / 12.14 ≈ 60%.
Current Equity/Total Capital = 4.89 / 12.14 ≈ 40%.

If they issued hybrids to reach the cap, they would replace senior debt or equity. Replacing senior debt with hybrids increases interest expense (hybrids are more expensive). Replacing equity is not possible via issuance (issuing hybrids raises cash, increasing assets and liabilities/equity mix).

Given the stable, regulated nature and the high interest rate environment shown in the data (making hybrids expensive), the company should be cautious. However, utilities often maintain a baseline of hybrids to support their credit rating metrics. A utilization of **50%** of the permitted cap is a prudent, balanced strategy that provides some equity credit benefit without overexposing the firm to high-cost capital or rating volatility. It is neither too aggressive (75-100%) nor too conservative (0-25%) for a major utility aiming for optimal WACC.

<answer>50%</answer>