Mark Hake, an analyst at Merrill Lynch said: "The UK building materials sector has had a pretty torrid year.... We could soon see a wave of consolidation, which is likely to be on a global basis."
Analysts say Rugby has become a takeover target because its strategy of transforming itself into a focused cement business has proved "messier and more drawn-out than expected".
Robin Hardy, an analyst at WestLB Panmure, said: "Rugby has been trading below its net asset value, at around 87p a share. That's bound to awaken people's interests." He valued Rugby at 125p-135p a share.
Possible suitors for Rugby include RMC or Blue Circle, Switzerland's Holderbank Financiere Glarus, France's Lafarge and Ireland's CRH. But Mr Hake said: "No one looks a racing certainty. I could come up with a dozen credible buyers."
Separately yesterday, Anglo American said it had ended talks to buy Tarmac. Nick von Schirnding, a senior vice president at Anglo American, said: "We have targeted the UK and parts of Europe as strategically interesting areas for us. That position still remains." Mr von Schirnding added that he had been "puzzled" by the announcement on Friday, when Tarmacsaid it had rejected Anglo's 535p a share approach, but failed to refer to the final, 550p offer, made on Friday afternoon.
Rugby shares closed unchanged at 114p yesterday, valuing it at pounds 743m. Tarmac dropped 24p to 488p and shares in Hepworth rose 9p to 197p on speculation it could be the next company in the sector to receive a takeover approach.