To determine S&P's adjusted leverage trend for Acciona SA, we compute the Net Debt to EBITDA ratio for 2021 and 2022 and calculate the year-over-year gap.

1. **Total Debt:**
- **2021 (Year-end):** 
  Noncurrent loans (2,073) + Current loans (280) + Noncurrent bonds/marketable securities (2,364) + Current bonds/marketable securities (1,666) + Noncurrent lease liabilities (430) + Current lease liabilities (68) = €6,881 million.
- **2022 (Year-end):** 
  Noncurrent loans (2,624) + Current loans (553) + Noncurrent bonds/marketable securities (3,101) + Current bonds/marketable securities (1,139) + Noncurrent lease liabilities (439) + Current lease liabilities (72) = €7,928 million.

2. **Net Debt:**
- Subtracting Cash and Cash Equivalents:
  **2021:** €6,881M - €2,318M = €4,563 million.
  **2022:** €7,928M - €2,360M = €5,568 million.

3. **EBITDA:**
- Using standard unadjusted calculations (Operating Profit + D&A):
  **2021:** EBIT (€829M) + D&A (€714M) = €1,543 million.
  **2022:** EBIT (€1,334M) + D&A (€762M) = €2,096 million.
*(Note: Acciona’s reported EBITDA reflects slightly stronger adjustments reaching €1,483M for 2021 and €2,068M for 2022. Both base and adjusted variants will yield a similar trajectory).*

4. **Net Debt / EBITDA Ratio:**
- **2021:** 4,563 / 1,543 ≈ 2.96x
- **2022:** 5,568 / 2,096 ≈ 2.66x

5. **Trend Analysis:**
- The year-over-year gap is 2.66x - 2.96x = -0.30x (or wider, reaching up to -0.39x if using the company's precise reported EBITDA definitions). 
- Since the ratio decreased by 0.3x or more (-0.30x drop), the metric is beyond the ±0.3x stable boundaries and firmly indicates an improving leverage profile.

<answer>Improving</answer>