VERBUND had a very strong 2022 operating year, with revenue more than doubling from €4.78bn to €10.35bn and EBITDA rising from €1.58bn to €3.16bn. Profit attributable to owners also nearly doubled to €1.72bn. Operating cash flow improved sharply to about €2.02bn, more than covering a large part of investing outflows of €1.59bn.

However, the balance sheet also shows meaningful capital needs and rising leverage:
- Total assets increased to €19.16bn.
- Equity increased to €8.32bn, but financial liabilities also rose materially.
- Noncurrent financial liabilities increased from €1.83bn to €2.84bn.
- Current financial liabilities remained high at €1.11bn.
- Total financial liabilities were therefore about €3.95bn at year-end 2022.
- Large capex and acquisitions continued, with investing cash outflow of €1.59bn and purchases/acquisitions over €1.5bn combined.

Hybrid bonds could be useful because they provide partial equity credit and support credit metrics while preserving liquidity for growth investment. But the company does not appear to need to maximize hybrid issuance:
- Equity is already substantial relative to debt.
- Profitability and cash generation are strong.
- The interest-rate environment deteriorated sharply in 2022, with swap rates moving from near-zero/negative levels to roughly 1.7–1.9%, and subordinated/hybrid-style spreads also increased. This raises the cost of hybrid capital.
- Maximizing the S&P cap would add expensive subordinated capital despite an already solid equity base.

So the optimal stance is moderate-to-high use, but not full utilization. A 50% usage of the S&P hybrid equity-credit cap seems appropriate: enough to strengthen adjusted capitalization and fund investment flexibility, but not so much that VERBUND overpays for hybrid capital in a higher-rate environment or unnecessarily complicates its capital structure.

<answer>50%</answer>