Explanation

Option A is correct because:

• The sensitivity of VaR to a position depends on two key factors:

  1. The share of the position in the portfolio - Larger positions have greater impact on portfolio VaR
  2. The sensitivity of the overall portfolio value to the position value - This relates to how changes in the position value affect the entire portfolio

• This relationship is mathematically expressed through the concept of marginal VaR or component VaR, where the contribution of each position to overall portfolio VaR depends on its weight and correlation with other positions.

Option B is incorrect because:

• Data scarcity can be a significant issue in sensitivity analysis
• While simulations can help, they still rely on historical data or model assumptions
• Real-world data limitations can affect the reliability of regression-based sensitivity tests

Option C is incorrect because:

• Sensitivity analysis focuses on how VaR changes with position sizes, not valuation choices
• Valuation choices would be examined through different types of analysis (e.g., model validation)

Option D is incorrect because:

• Large trading organizations often have rapidly changing portfolio compositions
• High-frequency trading and dynamic hedging strategies can cause frequent portfolio changes
• This dynamic nature makes sensitivity analysis challenging and requires frequent updates