The most liquid of the private investments are investing in equity or credit hedge funds, real estate funds, and private company funds. There will usually be 6 month – 3 year lockup periods. The least liquid of the private investments are when you invest directly into private companies yourself. You might not be able to get your money out for 5-10 years, depending on the success of the company and upcoming liquidity events.
For those willing to take on the task of managing a property, real estate can be a powerful semi-passive income stream due to the combination of rental and principal value appreciation. But to generate passive income from real estate, you either have to rent out a room in your house, rent out your entire house and rent elsewhere (seems counterproductive), or buy a rental property. It’s important to realize that owning your primary residence means you are neutral the real estate market. Renting means you are short the real estate market, and only after buying two or more properties are you actually long real estate.
Managerial accounting defines residual income in a corporate setting as the amount of leftover operating profit after all costs of capital used to generate the revenues have been paid. It is also considered the company's net operating income or the amount of profit that exceed its required rate of return. Residual income is normally used to assess the performance of a capital investment, team, department or business unit.