Iberdrola is a large regulated/renewables utility with substantial and growing capital expenditure needs, so hybrids can be useful to support credit metrics while avoiding common-equity dilution. The company already has material subordinated/perpetual capital instruments and non-controlling-interest funding, and its 2022 balance sheet is sizeable: equity of about EUR 58.1bn and financial liabilities of roughly EUR 69.3bn, implying total adjusted capital on the order of EUR 127bn before rating-agency adjustments. S&P’s 15% equity-credit cap would therefore represent a very large theoretical ceiling.

However, several factors argue against fully utilizing the cap:

- Leverage and funding needs increased in 2022, with noncurrent financial liabilities rising materially and heavy ongoing investment spending.
- Interest rates and credit spreads rose sharply in 2022; the 5Y/7Y/10Y swap curves moved from near-zero/negative levels to around 1.7%–1.9%, making new hybrid issuance materially more expensive.
- Hybrids help ratings, but they are still cash-coupon obligations and can become costly if overused.
- Iberdrola’s business profile is strong and defensive, with solid EBITDA and operating cash flow, so it does not appear to need maximum hybrid usage.
- Existing hybrid/perpetual instruments already contribute to capital structure support.

Overall, the company should use hybrids meaningfully but conservatively—enough to preserve rating flexibility and fund growth, but not so much as to approach the full S&P cap in a higher-rate environment. A moderate-to-high utilization of the cap is appropriate, but not maximum.

<answer>50%</answer>