The offer for Seven&i Holdings would create an international convenience store behemoth combining 7-Eleven, Couche Tard, Circle K and other brands across Asia, North America and Europe.

With a market value of ¥5.6 trillion (US$38.6 billion) as of Monday afternoon, it would also be one of the biggest foreign acquisitions of a Japanese firm.

Seven&i operates more than 85,000 stores around the world. Alimentation Couche-Tard (ACT) operates more than 16,700 in 31 countries and territories.

Seven&i in a statement gave no details on the size of the offer and said it has formed a special committee of independent outside directors to examine it.

“Neither the Board of Directors nor the Special Committee has made any determination at this time to either accept or reject the proposal from ACT, to enter into discussions with ACT or to pursue any alternative transaction,” it said.

The announcement came shortly after the Nikkei business daily broke the news earlier in the day, prompting Seven&i shares to skyrocket 22.71% to ¥2,161.

Before the news became public, Seven&i’s market capitalisation stood around ¥4.6 trillion, the Nikkei newspaper said.