Greencore shares jumped more than 5 per cent yesterday, rising to their highest closing price in at least seven years as more than three times the normal daily trading average changed hands.

The majority of trading, which occurred in lots of several hundred thousand each, was done by brokerage NCB. Market sources speculated that the buyer may be reclusive property developer Liam Carroll seeking to increase his 21.5 per cent stake in the group. A spokeswoman for Greencore was unable to confirm who was behind the trades.

The stock rose 23 cent, or 5.5 per cent, to €4.43. More than 3.6 million units traded, or 1.8 per cent of the issued share capital. At the closing price, one million units would have cost €4.43 million.

Mr Carroll, who bought his initial stake from businessman Dermot Desmond last summer for €170 million, is known to be interested in the group because of its property assets. However, Greencore last month announced plans to develop its former sugar plant in Carlow, a move believed to have been prompted by concerns that Mr Carroll was seeking to take over the company and strip out the property.

Greencore, which is focusing on the convenience food market since terminating sugar production, surprised the market when it revealed plans to redevelop the former sugar plant itself rather than selling the site or seeking a partner. The announcement of the €1.1 billion development was the first the group's shareholders had heard about its plans to enter the commercial property sector, and given that Greencore has 900 acres of surplus property, most likely not the last.

This week Greencore revealed operating profits excluding exceptionals of €74.6 million in the year to the end of September. Turnover from continuing operations was up 8.3 per cent, at €901.4 million.