Bill McEwan, CEO of Empire Co Ltd's Sobeys grocery store chain, is to retire because of a health problem.
McEwan, who has been in the role since 2000, will remain in position until the search for a replacement – which has already started – is complete.
Sobeys hopes to be able to announce his successor's appointment around May this year.
Empire chairman Rob Dexter said: "We will consider all suitable candidates and are fortunate to have very strong internal candidates."
