Wiktionary
golden share
n. A nominal share which is able to outvote all other shares in certain specified circumstances, often held by a government organization in a government company undergoing privatization and transformation into a stock company.
Wikipedia
Golden share
A golden share is a nominal share which is able to outvote all other shares in certain specified circumstances, often held by a government organization, in a government company undergoing the process of privatization and transformation into a stock-company.