The owner of 7-Eleven supermarkets and other retail chains has received a takeover offer from Canadian company Alimentation Couche-Tard.

Japan’s Seven and i Holdings said on Monday that a special committee of outside directors had been set up to review the offer, but did not provide further details.

Shares of Seven and In Tokyo, the share price rose 23%, the biggest daily increase in the company’s history.

“This potential takeover offer is a huge deal. 7-Eleven is the largest operator in the U.S. convenience store sector, with a 14.5% market share in 2023,” said Neil Saunders, managing director of GlobalData. “In comparison, Alimentation Couche-Tard’s brands had a 4.6% market share, so combining the two would create a company that controls almost a fifth of the market.”

The company has tried to streamline operations and sold the Sogo department store chain last year and Seibu Co. to a US investment fund.

Seven and I said that neither the Board nor the Special Committee had yet decided to accept or reject the offer, to enter into discussions with Couche-Tard or to pursue alternative options.

The company will make its decision public, it said on Monday.

Couche-Tard operates a number of convenience store chains under brand names such as Couche-Tard, Circle K and On the Run. The company has more than 14,000 stores in Canada, Ireland, Mexico, Russia, Poland, Norway, Sweden, Denmark and the United States.

Saunders said any takeover attempt would attract the attention of U.S. regulators.

“Because convenience stores are part of a much larger grocery and food market, there aren’t too many competition concerns,” Saunders said. “However, the level of concentration will almost certainly draw the FTC’s attention, which will not make this deal easy given the current negative sentiment around consolidation and competition in the grocery and basic needs sector.”