About 800 staff at Somerfield's Bristol headquarters are waiting to hear whether their jobs will be affected by the supermarket being taken over.
The Co-operative Group (Co-op), based in Manchester, has agreed to buy smaller Bristol-based Somerfield for £1.56bn.
Bristol business analyst Mike Warburton said: "Nobody runs two HQ operations".
Mr Warburton said: "The Co-op is doing this to cut costs, so they're going to look very hard at the HQ jobs".
Somerfield company spokesman Pete Williams said it was too early to tell about any job losses.
"Our combined power with Co-op's strength and Somerfield's position on the High Street will make us better and better," he added.
Somerfield's success in the supermarket business began through takeovers. The firm traces its roots to JH Mills, who opened five grocery stores in Bristol in 1875.
In 1950, the shops were renamed "Gateway" and became Somerfield in 1994. Somerfield now has 880 shops, including 150 on petrol forecourts.
Co-op chief executive Peter Marks said the Somerfield brand would disappear once the Office of Fair Trading had approved the deal.