Let’s break down the situation for Iberdrola based on the data and the guidelines provided.

**1. Business and Industry Context**
- Iberdrola is a major European integrated utility (Iberdrola, S.A., domiciled in Spain).
- The S&P methodology for regulated utilities, unregulated power and gas, and energy networks is relevant. Iberdrola operates a mix of regulated networks and unregulated renewable generation.
- As an electricity utility with large-scale networks and renewable generation, it likely falls under the "Regulated Utilities" and "Unregulated Power And Gas" frameworks. Many of its activities (networks, contracted renewables) have strong regulatory/policy support, providing cash flow predictability.

**2. Current Capital Structure and Hybrids**
- The balance sheet as of 2023-01-01 shows:
  - "Instrumentos De Capital Con Caracteristicas De Pasivo Financiero No Corriente": €576M
  - "Instrumentos De Capital Con Caracteristicas De Pasivo Financiero Corriente": €87M
  - Total hybrid-like instruments (perpetual subordinated with characteristics of financial liability) = €576M + €87M = €663M.
- In the equity movement, there is "Devengo De Intereses De Obligaciones Perpetuas Subordinadas" (accrual of interests on perpetual subordinated obligations) of -€169M in retained earnings and "Emision De Obligaciones Perpetuas Subordinadas" in prior year. This confirms existing hybrid instruments.
- Equity Attributable to Owners of Parent: €41,119M.
- Non-current Financial Liabilities: €44,216M.
- Total Adjusted Capital (Equity + Adjusted Debt) is much larger. Using simple equity + total financial debt (non-current + current financial liabilities): €58,114M + €44,216M + €25,079M = ~€127.4B (rough, not precisely S&P adjusted, but indicative). 15% of total adjusted capital would be a very large number, far exceeding the €3B/year practical cap and the existing ~€0.7B.
- The existing hybrid amount (~€0.66B) is a tiny fraction of total adjusted capital (likely well below 3.75%).

**3. Financial Performance and Credit Metrics**
- Revenue grew strongly from €39.1B to €53.9B, but raw materials costs also surged (€22B to €33.7B). Gross profit improved from €17.1B to €20.2B.
- EBITDA (Beneficio Bruto De Explotacion) increased from €12.0B to €13.2B.
- Finance Costs increased sharply from €2.27B to €3.04B (reflecting higher interest rates in 2022).
- Profit After Tax attributable to parent rose from €3.89B to €4.34B.
- Cash Flow from Operations: €10.44B in 2022 vs €8.11B in 2021.
- Investing Activities: -€10.15B (heavy capex, mainly in PPE: €6.28B purchases).
- Debt issuance and repayment: significant financing activities, but overall net cash from financing was only +€151M.
- Leverage: Debt is high (gross financial debt around €69B). Net debt/EBITDA or FFO/Debt metrics would need calculation, but the sharp rise in interest costs and large ongoing capex are credit-relevant pressures.

**4. Market Context (2022)**
- Interest rates rose sharply in 2022 (5Y swap from -0.26% to 1.73%, 10Y swap from 0.05% to 1.93%).
- Corporate bond yields (iShares Core Euro Corp Bond) rose from ~0.73% to ~1.09%.
- Subordinated (hybrid) spreads: Sub-Sen Delta for Non-Financial IG is 0.2%, implying hybrid cost is above senior debt. The cost of new hybrid issuance would be higher than in prior years, but the absolute level is still moderate historically.

**5. Rationale for Hybrid Issuance Extent**
- **Refinancing Needs & Capex**: Iberdrola has very high capex (€10B+ investing activities) and growing. They have large financial liabilities, part of which is short-term (€25B current financial liabilities). There is a clear need to fund capex and refinance maturities.
- **Leverage Management**: The surge in interest rates in 2022 and large debt load will pressure interest coverage metrics (Finance Costs up 34%). Issuing equity or equity-like instruments (hybrids) can help manage adjusted leverage metrics.
- **Existing Hybrids**: They already use hybrids (€663M), indicating familiarity and acceptance. The level is currently low relative to the 15% S&P cap.
- **Cost of Hybrid**: In 2022, the sub-senior delta for IG non-financials is ~1.2% over senior (0.2 delta on bond index yield ~1.1%, but actual pricing depends on the company’s credit spread). The cost of hybrid would moderately increase the current cost of debt (senior debt cost was low but rising). It does not "materially increase" the cost to a prohibitive extent, but it is higher.
- **Rating Profile**: Iberdrola is typically in the 'BBB+' or 'A-' range (strong investment grade). The guidelines for "A range" suggest 0% if no extraordinary needs, but Iberdrola does have *extraordinary capex needs* (€10B+ outflow, massive renewable investment). So it fits the case of a strong rating with high capex, benefiting from moderate hybrid use.
- **Guideline Alignment**:
  - Not 0%: They have high funding needs and moderate refinancing.
  - Not 15%: Rating is strong, no material downgrade risk, and cost of hybrid is not "in line" with current cost of debt (it's higher in 2022).
  - 3.75% to 7.5%: "Moderate funding needs" and "mild leverage optimization" vs. "moderately constrained headroom." Iberdrola’s headroom is reasonably comfortable (strong cash flow, high EBITDA), but rate sensitivity and heavy capex suggest "moderate refinancing needs" and some "leverage optimization rationale." Issuing another €1-2B in hybrids (toward 3.75%-7.5% of total adjusted capital) would provide rating flexibility. The total adjusted capital is huge (~€130B+), so even 3.75% is ~€4.9B. With a €3B/year issuance limit, and current ~€0.7B outstanding, moving toward 3.75% (total ~€4.9B) would mean issuing ~€4.2B over time, not in one year. In the next 18 months, a practical recommendation considering the cap and current level is to increase toward the lower end of the range but not aggressively given cost.
  - Given the cost is moderately higher than existing debt and the rating is strong, 3.75% fits "moderate funding needs, mild leverage optimization." 7.5% would be more aggressive and might imply "rating headroom moderately constrained." Iberdrola’s headroom is probably not critically constrained.

**6. Conclusion**
Iberdrola should continue to utilize hybrid bonds, but given its already strong credit profile and the increase in hybrid cost relative to historical levels, a moderate target of 3.75% of total adjusted capital over the medium term is appropriate. In the next 18 months, they might issue up to that level (which is significantly above current hybrid stock but still conservative relative to the 15% cap). This provides funding for capex and refinancing while keeping the cost of capital efficient.

<answer>3.75%</answer>