**Step 1: Identify the relevant industry**
Based on the provided facts, Fortum Oyj operates in the power and gas sector. Given the significant exposure to merchant risks (evidenced by the large gains/losses on derivatives and fair value changes), nuclear operations, and the nature of its assets, the most appropriate S&P industry classification from the provided methodologies is **Unregulated Power And Gas**. The methodology for Unregulated Power and Gas specifies standard adjustments for debt and EBITDA, largely in line with the baseline formulas, but also notes adjustments for long-term power purchase agreements (PPAs) if applicable, and specific volatility profiles. For the ratio calculation, the baseline formulas for Adjusted Debt and Adjusted EBITDA apply directly.

**Step 2: Estimate Adjusted Debt**
The baseline formula is: Adjusted_Debt = (reported_debt + leases + pension_deficit + guarantees + hybrid_debt_portion + other_debt_like_items) - eligible_cash

1. **Reported Debt**: We sum the financial liabilities from the balance sheet.
   - Other Noncurrent Financial Liabilities (2023-01-01): 3,658,000,000 EUR
   - Noncurrent Derivative Financial Liabilities (2023-01-01): 756,000,000 EUR
   - Other Current Financial Liabilities (2023-01-01): 4,127,000,000 EUR
   - Current Derivative Financial Liabilities (2023-01-01): 3,973,000,000 EUR
   Total Reported Debt = 3,658,000,000 + 756,000,000 + 4,127,000,000 + 3,973,000,000 = 12,514,000,000 EUR.

2. **Leases**: Typically estimated as 8x the rent expense if not directly stated. From the cash flow statement, "Repayments Of Non Current Borrowings And Repayments Of Lease Liabilities" is 5,888,000,000 EUR, and "Repayments Of Non Current Borrowings" can be deduced or we can look for operating lease right-of-use assets if provided. The facts don't give explicit operating lease liabilities separate from the standard lines, but under IFRS 16, lease liabilities are usually within financial liabilities. Assuming the reported financial liabilities already incorporate lease liabilities under IFRS, we make no further add-back (or if we were to reconstruct, we'd need the rent expense). Since we cannot segregate lease interest/principal perfectly without further detail, we use the reported debt figure which includes them.

3. **Pension Deficit**: 
   - Noncurrent Recognised Liabilities Defined Benefit Plan (2023-01-01): 13,000,000 EUR
   - (No current portion of defined benefit plan listed separately). 
   Pension Deficit Adjustment = 13,000,000 EUR.

4. **Guarantees & Hybrids**: None explicitly listed in the facts to adjust.

5. **Other Debt-Like Items**: Unfunded nuclear waste provisions are typically treated as debt-like in utilities. 
   - Nuclear Non Current Provisions (2023-01-01): 966,000,000 EUR.
   - Other Longterm Provisions (2023-01-01): 118,000,000 EUR.
   Total Provisions Adjustment = 1,084,000,000 EUR.

6. **Eligible Cash**: 
   - Liquid Funds (2023-01-01): 3,919,000,000 EUR.

*Calculation for Adjusted Debt*:
Adjusted_Debt = (12,514,000,000 + 13,000,000 + 1,084,000,000) - 3,919,000,000 = 9,692,000,000 EUR.

**Step 3: Estimate Adjusted EBITDA**
The baseline formula is: Adjusted_EBITDA = EBITDA + adjustment_leases + nonrecurring_losses - nonrecurring_gains ± pension_adjustments ± joint_venture_proportional_EBITDA ± other_normalization_adjustments

1. **Reported/Comparable EBITDA**: The facts directly provide "Comparable Ebitda" for the period 2022-01-01 to 2023-01-01: 2,436,000,000 EUR. This already adjusts for nonrecurring items ("Items Affecting Comparability" of -593,000,000 EUR, which includes impairments, capital gains, and fair value changes). 

2. **Lease Adjustment**: Under S&P methodology, 50% of the rent expense (or operating lease expense) is added back to EBITDA. Without explicit rent expense data, and assuming IFRS 16 lease costs are embedded in the operating costs (and thus reduce Comparable EBITDA), we lack the specific figure to add back. We rely on the reported Comparable EBITDA as the closest proxy.

3. **Joint Venture Proportional EBITDA**: S&P adds back the proportional EBITDA of equity-method investments and subtracts the equity income to avoid double counting. 
   - Share of Profit Loss of Associates and JVs (Equity Income): -629,000,000 EUR.
   - To estimate proportional EBITDA, we use the investment value and typical multiples, or we simply take the reported EBITDA as the anchor. Under S&P's ratios and adjustments, proportionally consolidating JVs requires specific debt/EBITDA data of the JV, which is not provided. We rely on the reported Comparable EBITDA of 2,436,000,000 EUR, keeping the -629M equity loss within it as per standard reporting treatment unless JV data is given. 

4. **Other Adjustments**: No further specific normalization adjustments are quantifiable from the provided text beyond what is already covered in the Comparable EBITDA.

*Calculation for Adjusted EBITDA*:
Adjusted_EBITDA = 2,436,000,000 EUR.

**Step 4: Calculate Adjusted Debt / Adjusted EBITDA ratio**
Ratio = Adjusted_Debt / Adjusted_EBITDA
Ratio = 9,692,000,000 / 2,436,000,000 = 3.97783...

Rounding to two decimal places, we get 3.98.

<answer>3.98</answer>