The lenders that bailed out Manchester Building Society two years ago have hired investment bank Rothschild to carry out a review of its finances.
The Sunday Times reports Rothschild has been brought in by Nationwide and the other lenders that supported the mutual when it was forced to raise £18m in April 2013.
The Manchester incurred huge losses after purchasing an interest-rate swap to protect it from movements in wholesale lending rates.
It raised the cash through profit-participating deferred shares.
The building society lost £1.6m in 2013 after taking an £8.7m write-down, the majority of which is thought to be connected to the swap.
In the first half of 2014 it made a £1.6m pre-tax profit, although it did not write any new mortgages over that period.
Nationwide and the other backers have called in Rothschild to conduct a valuation assessment on their investment. Sources say this is widely seen as a prelude to another fundraising by the Manchester.
The Manchester and Nationwide declined to comment. Rothschild could not be reached for comment.