Canadian retailer Hudson's Bay Co (HBC.TO) said on Thursday that the head of its international business, Don Watros, would leave the company at the end of September and did not name a successor.

Watros, who had previously served as HBC's chief operating officer, is the latest senior executive to leave the company in recent months. It comes as the Canadian retailer is struggling to revive sales and battling activist shareholder Jonathan Litt, who has called on the company to consider drastic options to make more money off its real estate assets.

HBC shares fell as much as 5.6 per cent to $10.01, on track for its biggest one-day fall since June 9 when it unveiled plans to overhaul operations amid a broader retail shakeup that has seen department stores across North America hurt by competition from online and discount retailers.

The benchmark Canada share index was up 0.2 per cent.

Watros has been with the company for 11 years, HBC said, and led its expansion into Europe in 2015 when it bought German department store chain, Galeria Kaufhof. The company has since expanded its Saks Off 5th brand into the region and is entering the Netherlands with the first Hudson's Bay stores outside of Canada.

HBC announced the departure of its chief financial officer, Paul Beesley, in May and appointed former J.C. Penney Co Inc (JCP.N) executive Edward Record last week to replace him.

In June, as part of HBC's restructuring announcement, the company said Brian Pall, the long-time head of real estate at HBC, was also leaving.

Litt, who through his investment vehicle Land and Buildings Investment Management LLC owns about 5 per cent stake in HBC, has warned he would consider a push to remove some of the company's directors after the two sides disagreed over how the company should move forward. In a letter to shareholders at the time, Litt said HBC should also exit Europe by selling Kaufhof real estate, operations or both.