Norwich & Peterborough Building Society (N&P) has admitted receiving a number of approaches from rivals this year keen to take over the firm, or take a significant stake.
In a statement this afternoon the building society said it was keeping the offers "under review".
Yorkshire Building Society is rumoured to be one of those which have approached N&P. It bought Chelsea, the UK's fifth biggest building society, earlier this year.
N&P chief executive Matthew Bullock has already said US private equity fund JC Flowers has been in touch. The US company has already promised to pump £50m into Kent Reliance Building Society.
"Like other responsible organisations, the board continually keeps under review, with its long-standing advisers, Fenchurch, all options for the society which could enhance the interests of members, customers and employees,"
N&P is facing mulit-million pound compensation claims from hundreds of investors who accuse it of mis-selling investments in Keydata, which went bust last year.
An ambitious objective
'Something completely new'
'Illusion of control'
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Total investment reaches £9m