Let’s reason this through step by step.

**1. Nature of the company**  
VERBUND AG is an Austrian electric utility with a large share of revenue from electricity sales and grid operations. Utilities tend to have stable, predictable cash flows, making them suitable for some degree of leverage—including hybrid debt—but they are also capital-intensive, so their credit profile must be carefully managed.

**2. Profitability and coverage**  
- EBITDA rose sharply from €1.58 billion (2021) to €3.16 billion (2022).
- Profit from operating activities rose from €1.27 billion to €2.63 billion.
- Interest expense increased from €78 million to €102 million.
- Interest coverage (EBITDA / interest expense) improved to over 30x in 2022, and even in the prior year was comfortably above 20x.  
This signals strong ability to service additional debt.

**3. Leverage and balance sheet**  
- Noncurrent financial liabilities increased from €1.83 billion (2021) to €2.84 billion (2022).
- Equity rose from €6.36 billion to €8.32 billion, so the debt-to-equity ratio remains moderate.
- Cash and equivalents increased, and operating cash flow was strongly positive in 2022 (~€2 billion).
- No obvious signs of over-leverage that would preclude hybrids, but a sharp increase in noncurrent derivative liabilities and some volatility in derivatives should be considered.

**4. Market conditions**  
- Swap rates rose dramatically from negative/low in 2020–2021 to around 1.7–2% in 2022, raising the cost of plain vanilla debt.
- Corporate bond yields (iShares Core Euro Corp Bond) averaged 1.085% in 2022 and subordinated spreads were higher (~2.3% for IG non-financials), meaning hybrids would carry a higher coupon.
- In a rising-rate environment, locking in long-term subordinated debt is less attractive unless the issuer specifically wants equity credit from rating agencies without diluting shareholders.

**5. Equity credit and rating considerations**  
- Utilities often issue hybrids to get 50% equity credit from rating agencies, improving or protecting credit metrics.
- Given VERBUND’s strong EBITDA, high interest coverage, and moderate leverage, a moderate (25–50%) reliance on hybrids would be plausible to optimize the capital structure without overpaying for subordinated debt.
- 0% would be too conservative given the cash flow stability; 75–100% would be unnecessarily expensive and riskier for refinancing.
- The sweet spot for a stable, investment-grade utility with strong coverage is usually around 25%, maybe up to 50%, but given rising rates and already adequate equity, the lower end of that range seems more prudent.

**Conclusion**: A 25% reliance on hybrid bonds would strike a good balance—taking advantage of the equity credit and diversifying funding without materially increasing overall cost of capital or risk.

<answer>25%</answer>