Which investment option is considered a non-allowable UITF investment outlet?

Promissory notes are considered a non-allowable investment outlet for UITFs because they do not align with the investment mandates typically defined for Unit Investment Trust Funds. UITFs are designed to primarily invest in securities and assets that are regulated and can be easily valued. This includes assets like corporate bonds and stocks of publicly traded companies which are well-established in the financial markets.

Promissory notes, while they represent a form of debt, often lack the liquidity and regulatory oversight that UITFs are expected to maintain. They are more akin to private agreements and can vary significantly in risk and return profiles, which goes against the more standardized approach required for managing UITF portfolios. Real estate investments also tend to be considered separately within UITF regulations, as they require different management and valuation processes compared to more liquid and regulated instruments. Thus, promissory notes don't meet the criteria set out for allowable UITF investments.