When a purchaser acquires a 100% interest of a business, included is complete control. THe purchase price includes a "control premium". Data suggests a premium of 30-40% above the value of freely-traded non-control minority interests. [Banister at 7]

If a purchaser acquires control, though less than 100%, the seller may still demand a control premium. This control can come in various sizes:

• controlling interest (typically 51% in a closely-held firm) gives majority control under most state corporate statutes
• blocking position (such as 34% when 2/3 majority voting is required) gives the purchaser a veto over fundamental corporate transactions, if supermajority voting is required under the corporate statutes or the company's articles or bylaws
• control block (15-20% in a typical publicly-traded firm) gives effective control over proxy voting in a public corporation, to elect board and approve other fundamental actions

The value of a less-than-100% controlling interest depends on the power it gives the purchaser under the firm's organizing law and constitutive documents, as well as the distribution of ownership in the firm.

Key man discount. A "one man" business may depress the value of the business, particularly if there is a lack of capable successors. In valuing this type of business, the risk of the loss of the manager and the absence of management succession are pertinent factors. Rev. Rul. 59-60.