Marks and Spencer Retail Financial Services could look to review its insurer relationships following its £762m purchase by HSBC.
Though companies like Allianz Cornhill, which underwrites the retail giant's credit card insurance, and Budget, which brokes the motor scheme, played down the change, industry sources said the question must now be asked.
An industry insider said: "It basically depends if there is a change of ownership clause in the contracts between the concerned parties.
"But why would M&S want to manage multiple relationships doing the same thing?
"It would be hard to see why HSBC would not try to link this in with other things they are doing."
But Phil Zeidler, managing director of Budget's affinity arm Junction, said: "We welcome the link with such a prestigious financial brand as HSBC.
"We have been advised that, in the short term, there will be no changes to the present relationship, and look forward to discussing the future with the new joint venture."
Marks and Spencer also works with AXA on its pet and travel insurance.