Holders of Nationwide “Pibs” – permanent interest-bearing shares – have in most cases been offered face value or more for their holdings. However, holders of one particular Pibs issue will suffer a “haircut” of almost 10% if they sell their investment back to the society, the Daily Telegraph reports.

Pibs are like corporate bonds in that they pay a set amount of interest yearly and trade on the stock market. However, they are “undated”, so there is no maturity date and normally the only way for holders to get their money back is to sell to another investor.

They also differ from the type of fixed-term bond sold to savers over the counter because they are not regarded as deposits with the bank or building society that issued them.

This means that there is no protection under the state deposit guarantee scheme if the lender goes bust. Fixed-term savings bonds are protected up to the £85,000 limit per person.

Five different issues of Nationwide Pibs can be sold back to the mutual under the offer. Two, the 6.875% and 7.25% issues, are redeemable at face value and one, the 7.859% version, will net investors more than face or “par” value, as they will be bought back at a 6.5% premium.

However, holders of two issues will get back less than par value if they redeem. The 6.25% Pibs will be bought back at 91% of face value, while holders of the 5.769% issue will suffer a 5% discount to par value.

The offers close on September 24 for private investors – those with no more than £100,000 in the Pibs.

Two other issues of Nationwide Pibs, paying 6% and 7.971%, are not included in the offer. They could already be redeemed at Nationwide’s discretion – or “called” in City jargon – in 2016 and 2015 respectively. “This suggests to us that Nationwide is likely either to call these on their due dates, or to make tender offers at a later date,” said Rik Edwards of Canaccord Genuity, the broker.