**Step 1: Identify the relevant industry**
NATURGY ENERGY GROUP SA is a multi-utility company involved in electricity and gas. Based on the provided methodologies, the relevant industry is "Regulated Utilities" (and potentially "Unregulated Power And Gas" for certain segments). The core financial ratio adjustments for utilities follow the Regulated Utilities methodology.

**Step 2: Estimate Adjusted_EBITDA**
Baseline formula: Adjusted_EBITDA = EBITDA + adjustment_leases + nonrecurring_losses - nonrecurring_gains ± pension_adjustments ± joint_venture_proportional_EBITDA ± other_normalization_adjustments
- EBITDA (Reported): 4,954,000,000 EUR
- Lease adjustment: Under S&P methodology, 1/3 of lease interest is added back to EBITDA. Finance costs are 837,000,000 EUR. Lease liabilities (Noncurrent: 1,325,000,000 EUR + Current: 196,000,000 EUR = 1,521,000,000 EUR). Assuming a roughly 5% implied interest rate on leases, lease interest is ~76,000,000 EUR. 1/3 of 76,000,000 EUR = ~25,000,000 EUR. 
- Other adjustments: We deduct nonrecurring gains. Gains on disposals (8,000,000 EUR) are non-core, so we subtract them. Other gains/losses (-111,000,000 EUR) and fair value changes (13,000,000 EUR) are typically considered part of the normalized utility earnings or mark-to-market for hedging, so no major further normalization is deducted. 
Adjusted_EBITDA = 4,954,000,000 + 25,000,000 - 8,000,000 = 4,971,000,000 EUR.

**Step 3: Estimate FFO**
Baseline formula: FFO = Adjusted_EBITDA - cash_interest - cash_taxes
- Adjusted_EBITDA: 4,971,000,000 EUR
- Cash Interest: Finance costs reported are 837,000,000 EUR. Cash interest paid (from cash flow statement) is 520,000,000 EUR. Under S&P methodology, FFO uses the cash basis for interest. However, standard S&P FFO calculation uses the reported interest expense adjusted for the lease add-back (i.e., Total reported finance costs 837,000,000 EUR minus 2/3 of lease interest ~50,000,000 EUR = ~787,000,000 EUR) to match the EBITDA add-back. Let's use the adjusted reported interest: 837,000,000 - 50,000,000 = 787,000,000 EUR.
- Cash Taxes: Income tax expense is 697,000,000 EUR. Cash taxes paid (from cash flow statement) are 762,000,000 EUR. S&P typically uses cash taxes paid for FFO if significantly different, or standard tax expense. Using the paid amount is more conservative and accurate for cash flow metrics: 762,000,000 EUR.
FFO = 4,971,000,000 - 787,000,000 - 762,000,000 = 3,422,000,000 EUR.

**Step 4: Estimate Adjusted_Debt**
Baseline formula: Adjusted_Debt = (reported_debt + leases + pension_deficit + guarantees + hybrid_debt_portion + other_debt_like_items) - eligible_cash
- Reported Debt: Long-term borrowings (13,786,000,000) + Current borrowings and current portion of noncurrent borrowings (1,493,000,000) = 15,279,000,000 EUR.
- Leases: Noncurrent lease liabilities (1,325,000,000) + Current lease liabilities (196,000,000) = 1,521,000,000 EUR.
- Pension deficit & other debt-like items: We look at noncurrent provisions (1,146,000,000) and current provisions (589,000,000) as potential debt-like items. Given the scale, we add a typical 75% of total provisions as debt-like obligations (0.75 * 1,735,000,000 = ~1,301,000,000 EUR). Also, typical Spanish utilities have significant debt-like derivatives; we observe "Pasivo Derivados Comerciales No Corriente" (730,000,000) + "Pasivo Derivados Comerciales Corriente" (2,704,000,000) = 3,434,000,000 EUR. Because these are largely hedging derivatives that net out against derivative assets (1,296,000,000 EUR), we don't add the gross liability. Instead, we add the net derivative liability: Net = 3,434,000,000 - 1,296,000,000 = 2,138,000,000 EUR. 
- Total Debt & Debt-like items = 15,279,000,000 + 1,521,000,000 + 1,301,000,000 + 2,138,000,000 = 20,239,000,000 EUR.
- Eligible Cash: Cash and Cash Equivalents = 3,965,000,000 EUR. We subtract this, as utilities typically do not have large restricted cash. 
Adjusted_Debt = 20,239,000,000 - 3,965,000,000 = 16,274,000,000 EUR.

**Step 5: Calculate FFO / Adjusted_Debt**
FFO / Adjusted_Debt = 3,422,000,000 / 16,274,000,000
Ratio = 0.21024

<answer>0.2102</answer>