Chloride Group has turned down a £723 million ($1.1 billion) approach from Emerson Electric with the US industrials group expected to sweeten its offer to seal a deal this time around.
Chloride was given only two days to respond to Emerson's proposal over the weekend. Emerson said its next step would be to contact the power protection firm's institutional shareholders.
Shares in Chloride surged 43 per cent to an all-time high of 300 pence, making them easily the top FTSE 250 riser.
According to analysts, the group would likely have to up its offer of 275 pence per share cash approach for the company, whose products protect against power shortages at Heathrow's Terminal 5 to at least 300 pence.
In an earlier bid, Emerson had offered 270 pence per share to Chloride, but the talks held in 2008 broke down after the development became public.
The offer although on the lower side in sterling terms, valued the company at about $1.3 billion in dollar terms at the time.