Source: Sharecast
According to Reuters, the New York-based private equity firm in December submitted an offer valuing the company at about 160p per share, but the Elementis board wanted around 180p.
At 1245 GMT, the shares were up 8.2% at 134.20p.
Elementis investor Franklin Mutual Advisers sent out a letter on Thursday expressing its "dismay" at the media report.
"In our view, this recent interest from KPS, coupled with prior offers from Minerals Technologies (130p, December 2020) and Innospec (160p, March 2021), again confirm Mutual Series' view that the company is a desirable acquisition target," it said.
"We believe this indication of interest should be the catalyst to launch a formal process to maximise shareholder value."
Franklin had already published a letter last September in which it urged Elementis to put itself up for sale.
It said on Thursday: "We are deeply concerned that, once again, the board does not appear to be acting in the best interests of its shareholders. It has been publicly reported that other significant investors share our views.
"We believe that the leadership team at Elementis is missing a valuable opportunity to maximise the value of the company. As we indicated in our letter dated September 20, 2023, and are reiterating today, we strongly urge the board to initiate a sales process immediately, and to engage with all potential buyers to maximize shareholder value."
