The STS x Finsceal Beo went for 800k.
Kingsfort is to stand at Azienda Agricola Casana in Italy for 2012
A foal from the first crop of Sea The Stars was sold for 800,000 euros at Goffs on Thursday.
The foal sale which began on Tuesday came alight on Thursday with the battle to purchase the filly who is out of three-time Group One winning mare Finsceal Beo.
She was the first offering from the brilliant son of Galileo who won eight of his nine starts, including the Prix de l'Arc de Triomphe, the Derby, the Eclipse and the Irish Champion Stakes.
Bidding started at 100,000 euros but quickly passed the half a million mark before being knocked down to agent John McCormack.
The second of his progeny to be offered was a colt out of Humilis, a Sadler's Wells mare who won a Listed race, and he, too, attracted plenty of interest before going to Blandford Bloodstock for 110,000 euros.
That was only the third highest sale on an exciting day at Goffs which also saw a daughter of Teofilo out of Grecian Bride sold for 200,000 euros to Sheikh Hamdan Al Maktoum's Derrinstown Stud.
The filly is a half-sister to Saddler's Rock who won the Group Two Doncaster Cup in September.
There was no such joy for the progeny of American Horse of the Year Curlin with the only foal catalogued to sell in Europe by him this year led out unsold at 74,000 euros.
There are another three foals of Sea The Stars still to go through the ring on Thursday.