(Reuters) - Asset manager Macquarie said on Thursday it is considering a possible cash offer for London-listed Renewi which would value the waste management firm at 636 million pounds (about $775 million).
Renewi's shares gained as much as 44% to touch a one-year high of 733 pence.
Macquarie's proposal of 775 pence per Renewi share made on Sept. 25 was rejected by the company's board, the Australian firm said.
In a statement, Renewi said it had considered the proposal in detail and believed it "fundamentally undervalues" the company.
($1 = 0.8203 pounds)