A spokeswoman for the bank confirmed a review was being conducted. Universal McCann was unavailable to confirm if it was repitching for the business.
In a statement, Sainsbury's Bank, which made profits of £21 million in 2002, said its marketing requirements were expanding to support the bank's growth.
As a result, it is also seeking new agencies to add to its roster.
It said: "Sainsbury's Bank can confirm that it is planning to extend its roster of agencies, including store merchandising and sales promotion. It is anticipated that new agencies will be brought on board from May."
Earlier this week, the supermarket bank appointed Agency.com to overhaul its website and online creative image following a four-way pitch.
The moves come as competition heats up between the major supermarket chains' financial products.
In January, Sainsbury's launched the first television campaign for Sainsbury's Bank through Abbott Mead Vickers BBDO featuring Jamie Oliver and friends.
In the same month, Tesco made its first push into promoting its financial products separately from its grocery ads in a £10 million television campaign through Lowe. The ads did away with Prunella Scales' "Dotty" character, instead featuring a range of animated trolleys with voice-overs by actors including David Jason.
Tesco Personal Finance made a pre-tax profit of £40 million last year.
Sainsbury's Bank said the roster extension would not affect its existing agency relationships.