Golden Share is a nominal share, held by a government organization, in a government company undergoing the process of privatization and transformation into a stock-company. This share gives the government organization the right of decisive vote, thus to veto all other shares, in a shareholders-meeting. Usually this will be implemented through clauses in a company's Articles of Association (law), and will be designed to prevent stakebuilding above a certain percentage ownership level, or to give a government veto powers over any major corporate action (such as the sale of a major asset or subsidiary or of the company as a whole).
This share is often retained only for some for some defined period of time to allow a newly privatised company to become accustomed to operating in a public environment, unless ownership of the organization concerned is deemed to be of ongoing importance to national interests (e.g. for reasons of national security).
The term arose in the 1980s when the British government retained golden shares in companies it privatised, and later in many other European countries.