Answer:
Explanation:
Portfolio managers typically have control over many aspects of portfolio construction, but there are certain elements that they do not directly control or select. Let's analyze the options provided:
1. **Client constraints**: Portfolio managers often need to adhere to client-specific constraints such as risk tolerance, investment objectives, liquidity needs, and ethical considerations. These constraints are crucial in shaping the portfolio's composition and investment decisions.
2. **Asset class weights**: Portfolio managers determine the allocation of assets across different asset classes (e.g., stocks, bonds, commodities). This decision is based on their outlook on market conditions, risk-return trade-offs, and investment strategy.
3. **Individual securities within asset classes**: Portfolio managers have the authority to select specific securities (e.g., stocks, bonds) within each asset class. They conduct research and analysis to identify securities that align with the portfolio's objectives and criteria.
4. **Individual securities across multiple asset classes**: This option refers to selecting specific securities that span different asset classes (e.g., a portfolio containing stocks, bonds, and commodities). Portfolio managers do have the discretion to choose securities from various asset classes to diversify the portfolio and manage risk.
**Exclusion:**
Given the options:
- **Client constraints** (Option 1) are typically considered by portfolio managers and influence their decisions.
- **Asset class weights** (Option 2) are determined by portfolio managers to achieve desired portfolio diversification and risk management.
- **Individual securities within asset classes** (Option 3) are selected by portfolio managers based on research and investment strategy.
- **Individual securities across multiple asset classes** (Option 4) are also within the purview of portfolio managers to achieve diversification goals.
The option that portfolio managers do not directly select or control is **none** of the above, as all options listed (1, 2, 3, and 4) are typically within the realm of their decision-making authority.