I'll analyze Ferrovial's capital structure and assess the appropriate level of hybrid bond reliance.

## Key Observations

**1. Existing Hybrid Usage:**
Ferrovial already uses perpetual subordinated bonds (hybrid instruments). The "Other Equity Securities" line shows ~€507-508M, which represents existing hybrid/perpetual subordinated bonds classified as equity. The statement of changes in equity shows "Perpetual Subordinated Bonds" transactions, confirming active hybrid bond usage.

**2. Capital Structure Analysis:**
- Total Equity: €6,354M (2023), including €508M in hybrid securities
- Total Assets: €26,284M
- Noncurrent borrowings: €10,776M (infrastructure project debt: €7,893M; ex-infrastructure: €2,883M)
- Current borrowings: €877M
- The company is heavily leveraged, primarily through infrastructure project finance debt

**3. Nature of Business:**
Ferrovial is an infrastructure concessionaire/constructor with:
- Large, long-duration infrastructure assets (€13.7B in infrastructure project investments)
- Significant project finance debt (ring-fenced at project level)
- Stable, predictable cash flows from toll roads and infrastructure concessions
- Strong operating cash flows (~€1B in 2022)

**4. Hybrid Bond Suitability:**
- Infrastructure companies benefit from hybrid bonds for equity credit from rating agencies while maintaining tax deductibility
- The company already has hybrids (~€508M) representing about 8% of equity attributable to parent
- The sub-senior delta for non-financial IG is 0.2, meaning the additional cost of subordination is moderate
- Rising interest rates in 2022 (swap curves moved significantly positive) make new issuance more expensive
- The company has significant non-recourse project finance debt, which is standard for infrastructure and reduces the need for hybrid at the corporate level

**5. Constraints:**
- Heavy reliance on project finance limits the need for corporate-level hybrid bonds
- Rating agencies typically give 50% equity credit to hybrids, but cap the benefit
- The company already has a modest hybrid program
- Too much hybrid would be costly given the spread premium and rising rates
- NCI of €2.2B suggests significant minority interests in projects, providing another form of quasi-equity

**Assessment:**
Ferrovial's existing ~€508M hybrid bonds represent a moderate, prudent use within its capital structure. Given the infrastructure-heavy business model with ring-fenced project finance, the company benefits from some hybrid usage for rating agency equity credit and financial flexibility, but doesn't need excessive amounts. A 25% allocation to hybrids within the capital structure optimization is appropriate - enough to benefit from equity credit without excessive subordination costs.

<answer>25%</answer>