Norway's finance ministry gave the go-ahead for the Oslo Stock Exchange to start selling its shares to investors in May.
The exchange had been planning the shift to public limited company status since last year.
This is in response to increasing worldwide competition between bourses.
All the other Nordic bourse partners in the Norex alliance - Stockholm, Copenhagen and Iceland - have been privatised.
"You're not a serious participant if you stay as a mutualised company," said Svein Arild Andersen, the OSE president. The aim was for more flexibility and speed. The exchange will start pre-marketing its shares to Norwegian and international institutional investors on April 17, followed by a subscription period from May 8-21.
The aim is to get a broad and varied shareholder base, with minimum offerings set at NKr300,000 ($32,858) and maximum stakes limited to 10 per cent.
Mr Andersen said it would welcome OM Gruppen, the Swedish technology and exchange operator which made a bid for the London Stock Exchange, as a shareholder.
The OSE plans to complete the privatisation process by August, when a new board will have been elected by the new shareholders. Later the exchange will allow strategic 25 per cent ownership stakes. However, at present it is not the intention for the stock exchange to be listed, Mr Andersen said.
The demutualisation comes as Oslo prepares for the privatisation of Statoil, Norway's state-owned oil company. After its listing in June, Statoil will become the largest company on the OSE, ousting Norwegian telecoms operator Telenor which listed in December at a value of NKr74bn.
Orkla Enskilda Securities is global co-ordinator for the Oslo Stock Exchange offering, while Christiania Markets is co-manager.