Daniel Loeb-led Third Point LLC has bought less than 5 percent stake in Japan’s second-largest grocery and retail group Seven & I Holdings Co., according to reports Tuesday. The move marks the U.S. hedge fund manager’s fifth foray into Japan in two years.

The billionaire activist investor has also urged the company to reform its supermarkets business, Japan's Kyodo News reported. Loeb wants the Tokyo-based retailer to downsize its general merchandise business to improve profitability.

It was not clear when Third Point acquired the stake, sources with knowledge of the matter told Reuters. Shares of Seven & I surged about 4 percent following the news. Both Third Point and Seven & I have reportedly declined to comment.

Loeb, who has also invested in Sony Corp., jet engine maker IHI Corp. and Suzuki Motor Corp., previously called for reforms at these companies. In a quarterly letter to investors in July, Loeb said Suzuki Motor is undervalued, considering its dominance in the Indian auto market. Earlier this year, the New York-based investor had pressured Japanese robot maker Fanuc Corp. to increase its dividend payouts.

Loeb, a supporter of Japanese Prime Minister Shinzo Abe’s efforts to improve corporate governance, has said Abe's policies will help investors get better returns by improving the way companies deploy cash.