Let’s break this down step-by-step.  

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**1. Understand the cap**  
S&P Global Ratings allows hybrid bonds to receive equity credit up to 15% of **total adjusted capital** (total debt + equity).  
The question is asking what percentage of this 15% cap the company should use.

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**2. Determine total adjusted capital for Ferrovial at end-2022**  

From the data:  
- **Total equity** (2023-01-01): €6,354M  
- **Total noncurrent borrowings** (excluding leases):  
  - Noncurrent debt securities & bank borrowings: €10,776M  
- **Current borrowings**: €877M  
- **Lease liabilities (noncurrent + current)**: €120M + €64M = €184M  

So total debt (approx.) = €10,776M + €877M + €184M = €11,837M  

Total adjusted capital = €6,354M + €11,837M = **€18,191M**  

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**3. Determine 15% cap in EUR**  
15% × €18,191M ≈ **€2,729M**  

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**4. Existing hybrids**  
From equity data, "Other Equity Securities" (perpetual subordinated bonds) at end-2022: €508M.  
These already qualify as hybrids for S&P.  

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**5. Room under cap**  
Remaining capacity under 15% rule = €2,729M – €508M ≈ €2,221M  

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**6. Market conditions**  
Interest rates have risen sharply in 2022 vs. 2020-2021 (swap curves up ~200 bps). Corporate bond yields also up.  
Higher rates make hybrid issuance more expensive, reducing incentive to issue more unless needed. The company’s leverage is moderate and cash flow generation (€1,002M operating cash flow) is solid.  

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**7. Conclusion on utilization**  
Given existing hybrids are already €508M (~19% of the cap), further issuance wouldn’t be maxed out unless needed for a large acquisition or capital plan. Issuing 100% of the remaining limit in this rate environment seems unlikely. A moderate increase (to 50% or 75% of cap) could be possible, but with no clear need for aggressive hybrid issuance, **75% of the cap** might be a plausible upper bound if they wanted to preserve rating headroom.  

However, "to what extent **should** this company utilize" suggests a more conservative approach: 50% is a balanced choice between flexibility and cost.  

Given the rate environment and existing hybrid stock, the most justifiable answer is:

<answer>50%</answer>