The Glasgow-based group said rival Host Europe, controlled by private equity firm Cinven, has made an indicative proposal regarding a possible offer at 300p a share.
The approach follows the announcement by Iomart last month that it had rejected two possible cash offers from Cinven of 275p and 285p, arguing that the advances “undervalued” the company. Shares jumped almost 5 per cent on the Alternative Investment Market, adding 12.5p at 279.75p.
Under City takeover rules, Host Europe had until Thursday to make a firm offer or walk away, but this deadline has now been extended to 16 September.
Meanwhile the FTSE 100 was led higher by the housebuilders as Persimmon matched the profits rise posted by smaller rival Bovis on Monday. Barratt Developments was up 10.4p at 368.6p and Persimmon added 15p at 1,350p.
Lower-than-expected inflation figures were also seen as positive for the housing market, putting back the need for a rise in interest rates. B&Q-owner Kingfisher was another beneficiary, up 11.2p at 310.6p. The FTSE 100 Index added 38.06 points to close at 6,779.31.
Jasper Lawler, market analyst at CMC, said: “Basic resources were by far the weakest sector as investors didn’t react well to BHP Billiton failing to announce an anticipated share-buyback plan due its divestment of non-core assets into a newly created company.”
BHP was the heaviest faller in the top flight, down almost 5 per cent at 1,965p. Fresnillo dipped 3 per cent to 973p, and commodities conglomerate Glencore dipped 1.5 per cent to 358.95p.