A UK financial institution, whose main activity is accepting deposits from the general public to finance mortgage lending on private housing. They also engage in some lending on commercial properties, and in other financial activities. Some provide current account facilities, including cheques and electronic transfers, for their depositors. Building societies have recently been permitted to transform themselves into companies, and several have done so, while others have chosen to remain mutuals. Building societies were the largest single source of mortgage finance until many transformed into banks. See also demutualization.