The offer of £842.4m, which was rejected by Shawbrook’s board in March, will remain open until May 26, Reuters reported.
At the time the offer was made, analysts warned it represented an undervalue.
If the offer is accepted, it would see Pollen Street Capital, in partnership with BC Partners, buy back the bank it took to flotation in April 2015.
A report by Digital Look, said Pollen’s Marlin Bidco consortium would need to obtain valid acceptances of at least 50% to allow it to push through the takeover.
A spokesperson for Shawbrook said there was no further statement at this time.
Pictured: Shawbrook chief executive Steve Pateman