Final answer:
Venture capitalists are the investor groups that supply funding to promising small companies for a share and managerial control, while also often advising on strategy and management.
Step-by-step explanation:
Investor groups that provide funding in exchange for a stake in the firm, and often, a degree of managerial control, are known as venture capitalists. These investors are involved because they believe in the potential for growth of small, yet promising companies. Venture capitalists gather funds from various sources, including individual and institutional investors such as banks, college endowments, insurance companies, and pension funds. They not only offer financial investments but may also give strategic advice and have an active role in managing the company. The belief in the companies' growth potential stems from the fact that they typically possess unique products or services that fill market needs, but require financial and strategic support to scale up operations.