To estimate the S&P credit trend for "REN - REDES ENERGÉTICAS NACIONAIS, SGPS, S.A." (REN), we follow the provided workflow:

### Step 1: Identify Industry
REN is a transmission system operator for electricity and natural gas in Portugal. This falls under **Regulated Utilities**.

### Steps 2–6: 2021 Financial Calculations
*   **Adjusted_EBITDA (2021):** Profit Loss from Operating Activities + Depreciation and Amortisation Expense = 218,863k + 241,940k = **460,803k EUR**.
*   **FFO (2021):** Adjusted_EBITDA - Finance Costs - Income Tax Expense = 460,803k - 54,356k - 52,081k = **354,366k EUR**.
*   **Adjusted_Debt (2021):** (Longterm Borrowings + Current Borrowings) - Cash and Cash Equivalents = (2,390,852k + 375,221k) - 398,759k = **2,367,314k EUR**.
*   **Debt/EBITDA (2021):** 2,367,314 / 460,803 = **5.14x**.
*   **FFO/Debt (2021):** 354,366 / 2,367,314 = **0.150**.

### Steps 7–11: 2022 Financial Calculations
*   **Adjusted_EBITDA (2022):** Profit Loss from Operating Activities + Depreciation and Amortisation Expense = 239,721k + 249,276k = **488,997k EUR**.
*   **FFO (2022):** Adjusted_EBITDA - Finance Costs - Income Tax Expense = 488,997k - 67,394k - 54,263k = **367,340k EUR**.
*   **Adjusted_Debt (2022):** (Longterm Borrowings + Current Borrowings) - Cash and Cash Equivalents = (1,695,362k + 638,944k) - 365,292k = **1,969,014k EUR**.
*   **Debt/EBITDA (2022):** 1,969,014 / 488,997 = **4.03x**.
*   **FFO/Debt (2022):** 367,340 / 1,969,014 = **0.187**.

### Step 12: Credit Trend Analysis
*   **Signal 1 (Leverage):** Ratio(2022) - Ratio(2021) = 4.03x - 5.14x = **-1.11x**. Since -1.11x ≤ -0.2x, this signal is **Improving**.
*   **Signal 2 (Coverage):** Ratio(2022) - Ratio(2021) = 0.187 - 0.150 = **+0.037**. Since +0.037 ≥ +0.03, this signal is **Improving**.

Both signals agree that the credit trend is improving.

<answer>Improving</answer>