Building materials giant CRH said yesterday that it did not believe there was anything significant underlying a recent rise in its share price.

The shares hit a high yesterday of €37.03, from an opening price of €35.35, before retreating somewhat to close at €36.30 with around five million units being traded.

On Thursday the stock jumped more than 6 per cent, with more than 3.3 million in equities changing hands.

A spokesman yesterday said the group believed there was nothing underlying the movement other than investors taking advantage of the fact that the shares were undervalued.

Unconfirmed reports yesterday had suggested that bloodstock magnate John Magnier, and his associate, racehorse owner and currency dealer JP McManus, had invested in the stock on the basis that it was undervalued.

Any party who buys 5 per cent or more of a quoted company must declare this to the market. By close of business last night, there had been no such disclosures.

Dealers attributed Thursday's jump to the fact that the overall sector was boosted by the news that Germany's Heidelberg Cement was considering a bid for British building materials firm, Hanson.

More than 12 million CRH shares were traded during the week, while the average bought and sold over the last six weeks was over nine million. However, two weeks ago over 15 million units changed hands.

In March and April CRH's price suffered on the back of concerns about a fall in US housebuilding activity, which was in turn tied to fears about a collapse in the sub-prime mortgage market.

However, the company has consistently pointed out that while over half its turnover is generated in the US, only around 15 per cent of this comes from supplying the house building industry.