Which of the following is NOT a type of commercial investment?

Private equity funds are indeed a form of investment but they do not typically fall under the category of commercial investments in the same way that the other options do. While private equity funds involve investing in companies or assets with the intent of driving growth and ultimately achieving a profitable exit, they are generally focused on equity rather than direct commercial activities such as property management or investment in commercial real estate.

Joint ventures, real estate investment trusts (REITs), and commercial mortgages are all directly associated with commercial real estate investment or financing. Joint ventures often involve collaboration between multiple parties to invest in a commercial project, REITs focus specifically on income-generating real estate and allow investors to earn a share of the income produced through commercial properties, and commercial mortgages are loans secured by commercial properties, directly facilitating real estate transactions. Thus, while private equity funds represent an important area of investment, they do not align as closely with the traditional definitions of commercial investment when compared to the other options listed.