HSBC has consolidated its global advertising account with WPP as "lead agency group partner".
Publicis Groupe, which shared some of the business with WPP, will continue to work on creative for the bank on a project basis.
The timing of HSBC’s decision is thought to be unrelated to the coronavirus outbreak.
The Asia-focused, British bank has been under scrutiny from investors for months as it battles to restructure itself and cut costs, and it has been searching for a new chief executive.
HSBC is said to have conducted the review at a holding company level during a closed process that began last year.
The bank said in a statement: "As part of our commitment to delivering world-class marketing, we have been conducting a review of our creative agency operating models. This is to ensure we have the right agency set-up to support our strategic goals and continue to build our brand.
"The dedicated project team has taken a robust and transparent approach throughout this process and, as a result, WPP group has been chosen as our lead agency group partner.
"We believe this new approach will help us manage our ‘one brand’ approach, as well as give markets access to the right skills and capabilities for specific business challenges. We will continue to work with Publicis Groupe on a project-by-project basis."
WPP and Publicis would not offer any comment.
WPP’s Wunderman Thompson has previously shared the duties on the advertising business with Publicis' Saatchi & Saatchi.
Another WPP ad agency, Grey, is also thought to look after some of HSBC’s creative work.
Two Publicis shops, Publicis.Sapient and Digitas, handle digital duties and it is thought that their role for HSBC will continue.
Publicis also recently picked up a brand assignment for HSBC in Singapore.
HSBC is a highly prized advertiser. Omnicom’s PHD won the global media account in 2018.