Carroll has been buying shares in the company almost daily since early August and now holds 5,975,157 shares, which amounts to a 24.82% stake in the company. He has paid between 24 and 25 per share for the stake, although last week began forking out as much as 25.75 for shares.

The publicity-shy developer hasn't made any declaration about his intentions regarding the company, but he is believed to be primarily interested in its 33-acre site at Dublin Port, which some believe has redevelopment potential.

Management buyout team Aella, which this week had its 24 per share bid rejected by shareholders, has said in the past that it doesn't believe the site can be redeveloped under the current long-term lease the firm has on the site. However, Carroll obviously thinks differently and is putting his money where its mouth is.

The rival bidding consortium, Moonduster, has hinted that it could be prepared to move the ICG facility out of Dublin Port. Philip Lynch, chief executive of One51, which is involved with Moonduster along with Doyle Shipping, told shareholders recently that Greenore in Louth could be developed as a deep water port as part of a cross-border initiative.

The value of the Dublin Port site has been one of the key factors driving up the company's share price since Aella's original 18.50 bid for the company. At last week's EGM, several shareholders urged institutional investors not to sell out at a low cost, citing new estimates by UCD urban planning and development lecturer Dr Brendan Williams, who said the land could be worth 30m per acre, which would value the site at 990m.

The new valuation dwarfs the 16.48m per acre achieved for the nearby Irish Glass Bottles site at Ringsend in 2006. It drew some sceptical comment from John McGuckian, the independent director who chaired the EGM, who said he had never heard of Dr Williams or the valuation before.

Despite the high estimates of the site's value, there is no concrete indication that ICG could relocate any time soon. At a recent results presentation, Dublin Port chief executive Enda Connellan said he couldn't see how ICG could easily transfer operations elsewhere and said his intention was to grow the port at its current location. Dublin Port plans to spend 100m over the next five years expanding operations. Any move of Dublin Port could also be stymied by the fact that the government has spent 750m on the recently opened Port Tunnel, which takes heavy goods traffic to the port.

However, despite Connellan's assertions, it could still eventually move. Prior to the recent general election, former tanaiste Michael McDowell suggested the port could move to north Dublin and Fianna Fail gave a commitment to assess all options for the port, including relocation. The most obvious candidate is Bremore, where Drogheda Port and Treasury Holdings plan to develop a new deep water facility. Should such a move ever transpire, relocation costs and prior investment in Dublin Port could be offset by the huge property bonanza that would ensue.

With the amount of money Carroll is pouring into ICG, he obviously must have a strong reason to believe the port will eventually go. However, if his big gamble doesn't pay off, he could still walk away with a profit, since any successful bid for the company will probably now exceed 25.40. Carroll could make around 5m if he sold his stake.