As with any investor, it can be expected that an angel investor would only put his money into a business that would provide the least risk on his investment. This is reflected in the investment decisions that such an investor would make, especially in the types of products or services that a business provides. Usually, angel investors invest in businesses that have the potential for long-term profitability. In recent years, the preference of angel investors has been in medical devices and medical related services, including medical billing services.