To determine the S&P credit trend for Terna S.p.A. from 2021 to 2022, we estimate the Adjusted EBITDA, FFO, and Adjusted Debt based on the provided annual report facts and S&P guidelines for Regulated Utilities.

**Step 1: Estimate 2021 & 2022 Adjusted EBITDA**
Adjusted EBITDA is roughly equal to the operating profit plus depreciation, amortization, and impairment losses.
* **2021:** 
  * Profit from Operating Activities = 1,200.4M EUR
  * Depreciation, Amortisation, and Impairment = 654.4M EUR
  * **Adjusted EBITDA (2021)** = 1,200.4M + 654.4M = **1,854.8M EUR**
* **2022:** 
  * Profit from Operating Activities = 1,333.5M EUR
  * Depreciation, Amortisation, and Impairment = 725.7M EUR
  * **Adjusted EBITDA (2022)** = 1,333.5M + 725.7M = **2,059.2M EUR**

**Step 2: Estimate 2021 & 2022 Funds From Operations (FFO)**
FFO is estimated as Adjusted EBITDA minus cash interest (net) and cash taxes.
* **2021:**
  * Net Cash Interest = Interest Paid (214.6M) - Interest Received (54.3M) = 160.3M EUR
  * Cash Taxes Paid = 317.9M EUR
  * **FFO (2021)** = 1,854.8M - 160.3M - 317.9M = **1,376.6M EUR**
* **2022:**
  * Net Cash Interest = Interest Paid (154.8M) - Interest Received (64.2M) = 90.6M EUR
  * Cash Taxes Paid = 380.1M EUR
  * **FFO (2022)** = 2,059.2M - 90.6M - 380.1M = **1,588.5M EUR**

**Step 3: Estimate 2021 & 2022 Adjusted Debt**
Adjusted Debt = Gross Borrowings + Financial Liabilities + Provisions for Employee Benefits (Pensions) + Hybrid Equity Portion (50%) - Cash & Short-Term Financial Assets.
* **2021:**
  * Borrowings & Financial Liabilities = Long-term (8,835M) + Short-term (1,947M) + Current Portion (1,640M) + Noncurrent Fin. Liab. (83.7M) + Current Fin. Liab. (45.8M) = 12,551.5M EUR
  * Provisions for Employee Benefits = 60.8M EUR
  * Gross Debt = 12,612.3M EUR
  * Less: Cash & Equivalents (1,566.8M) + Current Financial Assets (980.6M) = 2,547.4M EUR
  * **Adjusted Debt (2021)** = 12,612.3M - 2,547.4M = **10,064.9M EUR**
* **2022:**
  * Borrowings & Financial Liabilities = Long-term (8,416.7M) + Short-term (444.1M) + Current Portion (1,909.3M) + Noncurrent Fin. Liab. (247.2M) + Current Fin. Liab. (44.9M) = 11,062.2M EUR
  * Provisions for Employee Benefits = 48.4M EUR
  * Add: 50% of the Perpetual Hybrid Bonds issued in 2022 (0.5 * 989M) = 494.5M EUR
  * Gross Debt = 11,605.1M EUR
  * Less: Cash & Equivalents (2,155.1M) + Current Financial Assets (255.3M) = 2,410.4M EUR
  * **Adjusted Debt (2022)** = 11,605.1M - 2,410.4M = **9,194.7M EUR**

**Step 4: Calculate Core Ratios and Evaluate the Trend**
* **Leverage (Adjusted Debt / Adjusted EBITDA):**
  * 2021: 10,064.9M / 1,854.8M = **5.43x**
  * 2022: 9,194.7M / 2,059.2M = **4.46x**
  * *Change:* -0.97x (A decrease of ≥ 0.20x represents an **Improving** signal)

* **Cash-Flow Coverage (FFO / Adjusted Debt):**
  * 2021: 1,376.6M / 10,064.9M = **13.68%**
  * 2022: 1,588.5M / 9,194.7M = **17.28%**
  * *Change:* +3.60 percentage points (+0.036 in decimal). (An increase of ≥ 0.03 represents an **Improving** signal)

**Conclusion:** 
With EBITDA rising substantially on the back of operational growth, and Adjusted Debt falling notably through cash conversion and optimized capital structure (including a hybrid issuance), leverage improved by nearly a full turn and coverage rose considerably. Both metrics provide strong, converging signals of an improved credit profile.

<answer>Improving</answer>