Cosmo Energy Jumps Most on Record as Murakami Fund Takes Stake

Shares of Japanese oil refiner Cosmo Energy Holdings Co. surged as much as 18% on Wednesday, the most on record, after a fund linked to activist investor Yoshiaki Murakami disclosed a stake in the company.

City Index Eleventh said it held a joint 5.8% stake in Cosmo Energy, according to a filing Tuesday. The fund acquired a smaller stake on March 10 after the oil refiner said that Abu Dhabi’s International Petroleum Investment was selling its entire stake. The Japanese fund bought additional shares that month.

Shares of peer refiner Fuji Oil Co. jumped as much as 11% in Tokyo, ...