Hochtief owns 54% of Leighton, and there are reports suggesting that outgoing Leighton chief executive Wal King, who spent 45 years with the company, might secure a role with ACS.

In the event ACS completes its acquisition of Hochtief, UBS analyst John Freedman told Dow Jones Newswires that ACS was unlikely to either sell or increase the 54% stake of Leighton, as the Spanish construction firm has a history of holding onto its stakes and also used its own stock for the takeover bid.

Leighton is well poised for growth, with its exposure to Mongolia’s growing coal industry forming just one ace in hand.

Apart from its construction activity, Leighton is also a big player in the mine operating game, especially through its subsidiaries Thiess and John Holland.

Thiess is also the major shareholder of engineering and coal wash plant specialist Sedgman.

King’s resignation is effective on the first day of 2011 and he will be replaced by Leighton’s chief operating officer David Stewart.

Leighton shares are up 47c to $34.04.