TORONTO (Reuters) - Loblaw Co, Canada's biggest grocer, has shaken up its executive suite in the face of sharp competition in the supermarket business, announcing on Monday that Deputy Chairman Allan Leighton will take on the role of president of the company, replacing Mark Foote.

The company also said Chief Financial Officer William Wells will leave to become chief executive of drugmaker Biovail Corp(BVF.TO: Quote, Profile, Research), where he was already an outside director.

Wells' job will be filled by Bob Vaux, CFO of parent company George Weston Ltd (WN.TO: Quote, Profile, Research), who will take on the additional role until further notice.

Pietro Satriano, executive vice president of food, will leave the company, Loblaw said.

The changes come after Loblaw has slashed prices to keep up with Wal-Mart (WMT.N: Quote, Profile, Research), which is opening several Canadian supercenters that sell food, as well as intense competition from Canadian rivals.

Shares of Loblaw were down C$2.13, or 6.7 percent, at C$29.60 on Monday afternoon on the Toronto Stock Exchange. The stock has lost about 44 percent of its value over the past year.

Loblaw is also overhauling its supply chain, closing some stores and cutting 1,000 jobs to try to improve results.

"At this crucial juncture, we require more focus and clarity in our leadership structure," Leighton said in a statement. "These changes will provide this."

Frank Rocchetti, executive vice president of general merchandise, will take over Foote's role as chief merchandising officer and will report to Leighton, who will also continue in his role of deputy chairman.