Let’s break down the situation for Veolia Environnement step by step.

**1. Current Capital Structure and Hybrids**
- “Titres Super Subordonnés à Durée Indéterminée” (deeply subordinated securities, i.e., hybrids) at 2023-01-01 (FY22 close): €3,496.3m.
- Total Equity at FY22 close: €14,866.9m.
- Total Assets: €73,304.1m.
- We need to estimate “total adjusted capital” = Equity + Adjusted Debt.
- Adjusted debt is not directly given, but we can approximate gross debt.
  - Noncurrent financial liabilities (excl. concession): €19,692.1m
  - Noncurrent lease liabilities: €1,656.2m
  - Current financial liabilities (excl. concession): €6,521.4m
  - Current lease liabilities: €496.5m
  - Bank overdrafts: €213.6m
  - Total gross debt ≈ €28,579.8m
- So approximate total adjusted capital = €14,866.9m + €28,579.8m ≈ €43,446.7m.
- Existing hybrids as % of total adjusted capital ≈ €3,496.3m / €43,446.7m ≈ 8.0%.
- This already exceeds the 7.5% option, pointing toward a higher issuance bracket if further hybrid issuance is needed.

**2. Business Profile**
- Veolia is a global environmental services leader (water, waste, energy).
- The Suez acquisition in 2022 was transformative; goodwill jumped from €6.2bn to €11.6bn, total assets grew ~38%.
- Regulatory advantage: Veolia operates many regulated or concession-based contracts, often with cost pass-through or inflation indexation. However, it also has unregulated, competitive businesses.
- Scale, scope, and diversity: Very large, global presence, diverse customer base.
- Profitability and cash flow: Operating income improved strongly in 2022 (€2.2bn vs €1.2bn). Net debt will be high post-acquisition.

**3. Financial Profile and Credit Metrics**
- The large Suez acquisition was financed partly with debt; net debt likely increased significantly. Veolia repaid some hybrids (-€500m) but also integrated Suez hybrids (+€1,623.9m).
- Interest rates have risen; 5Y euro swap went from negative to ~1.7% average in 2022, 10Y to ~1.9%. Corporate bond spreads widened.
- FFO to debt and debt to EBITDA will be under pressure. Veolia likely needs to deleverage.
- The guidance mentions “Investment grade preservation strongly dependent on capital structure optimization” for the 11.25% bucket; Veolia is a solid investment grade but the large acquisition could stretch its metrics toward the lower end of IG.
- S&P normally caps hybrid equity credit at 15% of adjusted capital. With ~8% already, additional issuance could push it toward the cap.

**4. Refinancing and Funding Needs**
- 2023 onward: likely high capex for energy transition, digitalization, hazardous waste treatment.
- M&A integration costs and potential bolt-on acquisitions.
- Veolia has significant maturing debt and may wish to refinance with equity-credit efficient instruments.
- The cost of hybrid debt has increased, but given the rise in senior debt costs, the relative penalty of hybrid vs senior has not necessarily widened proportionally. Veolia’s existing hybrids pay coupons, and market data shows sub-senior spread delta ~0.2% over corporate bonds, making hybrids relatively attractive for rating support.

**5. Matching to the Guidance Table**
- **15%** is for “Very high refinancing needs OR transformational capex/M&A program; Material downgrade risk without hybrid support”. Veolia’s Suez acquisition is already done; it’s now in integration/deleveraging. Not a further transformational M&A.
- **11.25%** fits “High capex intensity OR large acquisition pipeline; Significant leverage pressure; Investment grade preservation strongly dependent on capital structure optimization”. That matches Veolia’s post-acquisition profile well.
- **7.5%** would be “Moderate refinancing or acquisition needs; Rating headroom moderately constrained”. Veolia’s needs and leverage pressure are more than moderate given the scale of Suez integration and rising rates.
- Thus, targeting a total hybrid proportion of up to 11.25% of adjusted capital (which allows some additional issuance beyond the current ~8%) seems appropriate.

**Final Answer**
<answer>11.25%</answer>