Which investment type is NOT typically a feature of investment funds?

Investment funds are typically designed to pool money from multiple investors to invest in a diversified portfolio of assets, which can include a variety of securities and other investments. The correct answer highlights that collectible art pieces are not a typical feature of investment funds.

Investment funds generally focus on liquid, standardized investments that can be easily bought and sold on the markets. Corporate bonds, real estate investment trusts (REITs), and exchange-traded funds (ETFs) all fall under this category as they can be part of an investment fund's portfolio. These investment types are structured, regulated, and often traded on formal exchanges, making them suitable for investment fund vehicles.

In contrast, collectible art pieces are unique, illiquid assets that do not conform to the standardization and marketability associated with typical investment fund holdings. Art investment usually requires specialized knowledge and carries higher risks related to valuation and market fluctuations, making it less compatible with the pooled investment strategy of most funds.