ENI S.p.A. currently carries a moderate level of financial leverage, with total financial debt of roughly €31.9 bn against equity of €55.2 bn, giving a debt‑to‑capital ratio around 0.58. Its operating cash flow is strong (≈ €17.5 bn in 2022) and interest coverage is comfortable, indicating limited need for additional equity‑like capital. Under S&P Global Ratings’ methodology, hybrid bonds can receive equity credit up to 15 % of total adjusted capital (debt + equity). With total adjusted capital of roughly €87 bn, the maximum equity credit allowed is about €13 bn. Existing hybrid instruments (perpetual subordinated bonds) provide an estimated equity credit of only ~2–3 % of capital, leaving ample headroom. 

Market conditions in 2022 feature positive swap rates (5‑yr average ≈ 1.7 %) and elevated sub‑ordinated spreads (iBoxx non‑financial IG sub‑senior delta ≈ 2.3 %). Hybrid yields would therefore be appreciably higher than senior debt costs, making new hybrid issuance expensive relative to conventional debt. Moreover, S&P’s guidelines treat hybrids as part of the capital structure only when they meet strict deferrability and permanence criteria; excessive use could signal higher financial risk and potentially trigger rating pressure.

Given the company’s robust cash generation, low leverage, and the high cost of hybrid financing, a conservative approach is warranted. Utilizing only a modest portion of the allowable equity‑credit capacity balances the benefits of occasional hybrid issuance (e.g., maintaining a diversified capital mix) against the cost penalty. Targeting roughly one‑quarter of the S&P‑allowed cap provides sufficient flexibility without over‑leveraging the balance sheet.

<answer>25%</answer>