SOK Corporation consists of SOK (Suomen Osuuskauppojen Keskuskunta) and its subsidiaries. SOK produces joint service and support activities in a centralised manner as well as develops and steers the strategies of S Group. In addition to its regional and national subsidiaries, SOK operates in the supermarket, tourism and hospitality trades in the Baltic area and St Petersburg.

SOK is a Finnish cooperative whose decision-making and administration comply with the Cooperatives Act, other regulations pertaining to its respective business areas as well as SOK's rules.The operations of the subsidiaries are regulated by, among other things, the Limited Liability Companies Act and the corporate principles that steer the operations of the entire corporation.The regional cooperatives own SOK.

SOK was founded in 1904.