Which of the following is not allowed for UITF investments?

In the context of Unit Investment Trust Funds (UITFs), investments are generally limited to certain asset classes that ensure compliance with regulatory guidelines and maintain the intent of a UITF structure. UITFs can invest in a variety of financial instruments, including stocks, bonds, and sometimes even real estate, depending on the specific UITF mandate.

Loans are not considered an acceptable investment for UITFs because they do not align with the typical investment strategy of UITFs, which focus on collecting funds from investors to buy securities or financial assets that are easily tradable and regulated. The nature of loans introduces risks and complexities that are not consistent with the investment vehicle's goal to pool resources for shared investment in traditional securities.

Therefore, loans are excluded from the permissible investments for UITFs, making this option the correct choice in identifying what is not allowed for UITF investments.