I'll analyze Bouygues' financial position to determine the optimal hybrid bond utilization relative to S&P's 15% cap on equity credit for hybrids.

## Key Financial Metrics (End of 2022, i.e., 2023-01-01 balance sheet)

**Leverage:**
- Total Equity: €13,932M
- Long-term Borrowings: €11,586M
- Current Borrowings: €1,361M
- Current Overdrafts: €418M
- Total Debt (approximate): ~€13,365M
- Net Debt: €7,440M (up dramatically from €941M in prior year)
- Total Adjusted Capital (Debt + Equity): ~€27,297M

**The dramatic increase in net debt** (from €941M to €7,440M) is largely driven by the massive acquisition activity in 2022 (€6,269M in cash flows used in obtaining control of subsidiaries - likely the Equans acquisition). Goodwill jumped from €7,446M to €12,626M, confirming a major acquisition.

**Profitability:**
- Revenue grew from €37.6B to €44.3B (+18%)
- Operating profit (recurring): €1,962M (up from €1,693M)
- Net profit attributable to owners: €973M (down from €1,125M)
- The decline in net profit despite revenue growth reflects higher financing costs and negative equity method contributions

**Debt/Equity ratio:** ~96% (significantly leveraged post-acquisition)
- Net debt/EBITDA (approximating EBITDA as operating profit + D&A ≈ €1,962M + €2,228M + €446M ≈ €4,636M): ~1.6x

**S&P's 15% cap calculation:**
- 15% × €27,297M = ~€4,095M maximum equity credit from hybrids

**Reasoning for hybrid utilization:**

1. **Post-acquisition leverage is elevated** - Net debt surged to €7.4B from under €1B, suggesting the company needs to manage its capital structure carefully. Hybrids could help optimize the debt/equity balance without diluting shareholders.

2. **Investment-grade profile** - Bouygues is a large, diversified conglomerate with stable cash flows across construction, telecom, and media. This supports hybrid issuance at reasonable spreads.

3. **Market conditions** - The 2022 swap curves show significantly higher rates (5Y at 1.726%, 10Y at 1.927%), and corporate bond spreads have widened. The sub-senior delta of 0.2 (20bps) for non-financial IG hybrids is relatively modest, suggesting hybrid markets are functioning but costs have risen.

4. **Need for capital structure optimization** - With the Equans acquisition dramatically increasing leverage, Bouygues would benefit from hybrid issuance to receive equity credit and improve credit metrics. However, the higher rate environment makes full utilization more expensive.

5. **Cash flow generation is solid** - Operating cash flows of ~€3B support debt servicing, but the company already has significant financing obligations (€441M lease payments, €260M interest).

6. **Balanced approach warranted** - The company has a clear need for equity credit given post-acquisition leverage, but the elevated rate environment and already-high debt load suggest a moderate rather than maximum approach. Full utilization might be excessive given the cost, but zero would miss an opportunity to improve credit metrics during a period of elevated leverage.

Given the significant post-acquisition leverage increase, strong business profile, and reasonable but elevated hybrid costs, I'd expect Bouygues to utilize a meaningful portion of the hybrid capacity - likely around 50-75% - to help manage credit metrics without over-burdening the cost structure.

The company's need to restore credit metrics post-Equans acquisition is strong, but the rising rate environment and already substantial debt load suggest a moderate-to-high utilization level.

<answer>75%</answer>