They have acquired the entire issued share capital of Prestige Finance and Swingcastle Ltd, specialist second charge mortgage lenders, which have combined gross assets of £68.1 million.
Prestige, a well-established secured loan lender, rebranded from Sheldon & Stern in 2002 and were funded by HBOS and Barclays.
OneSavings published an announcement in July that suggested growth, having issued shares to the value of £15 million, with chairman Stephan Wilcke commenting at the time:
"The Board is pleased that it has secured a further planned capital injection from JC Flowers to pursue its growth strategy. This is a perfect example of the significant benefits that the Bank's hybrid structure delivers by providing access to capital whilst staying close to its mutual values."