A Company in which the public are not substantially interested is known as a 'Closely Held Company'.
It is not a defined term. Generally, when a small number of shareholders own a company, it is called a closely held company. It is also informally known as a Privately held company.
The opposite of a closely held company is widely held companies in which public are substantially interested. Taxation: A closely held company do not enjoy as much tax benefits as a widely held company is allowed to.