Final answer:
A corporation with stock held by a small group of people, not traded on national exchanges, is known as a closely held corporation.
Step-by-step explanation:
A corporation whose stock is not traded on the national securities exchanges but is held by a small group of people is a closely held corporation. This type of corporate stock differs from that of publicly held corporations, where shares are available to the general public through a stock exchange. Closely held corporations are more private in nature, often run by family, friends, or a small group of investors, and do not publicly issue stock.