Rentokil Initial Plc rallied on Friday after activist investor Nelson Peltz's Trian Fund Management bought 7.5m shares in the pest control company for £31m.
The shares were purchased at 413.4p each on 11 December.
At 1155 GMT, Rentokil shares were up 3.7% at 414p, having jumped to as high as 415.30p earlier.
Trian took a 2.26% stake in Rentokil in June and in September, the company announced the appointment of a representative of Trian to its board as a non-executive director, sending the shares surging.