The Aidan O'Brien-trained Magician will be retired to Ashford Stud in Kentucky after he attempts to defend his Breeders' Cup Turf crown at Santa Anita.
By Galileo, the four-year-old rose to prominence by winning the Dee Stakes at Chester last May and the Irish 2000 Guineas just two weeks later.
He disappointed in the St James's Palace Stakes at Royal Ascot and was not seen again until his finest hour at Santa Anita where he came with a late run to deny The Fugue.
This season he finished second in the Prince of Wales's Stakes to The Fugue and he also went close in the Arlington Million.
"Magician is a very, very good-looking horse who possesses a blistering turn of foot," Ashford's director of sales, Charlie O'Connor, said on the Coolmore website.
"Along with Frankel he's one of only three colts by Galileo to win a Classic over a mile so he's a rare commodity."