Irish Flat champion jockey Jamie Spencer has resigned as stable jockey with Aidan O'Brien.
Spencer won the Irish Flat jockey's title last year
The 24-year-old was heavily criticised for some of his rides in his first season with O'Brien, although he won the Irish championship.
Coolmore spokesman Richard Henry confirmed the news in a statement, saying: "Jamie is a talented jockey with a long career ahead of him.
"All the team at Ballydoyle wish him the very best."
Spencer was disqualified on Powerscourt after finishing first in the Arlington Million, and was then criticised by some for committing too early on him in the Breeders' Cup Turf.
He also came under fire in some quarters for his ride on the frustrating Antonius Pius, who finished second in the Breeders' Cup Mile.
However, he claimed Group One wins in the Middle Park Stakes and the Prix Jean-Luc Lagardere late in the season.
Irish bookmakers Cashmans had suspended betting on this year's Irish jockeys' championship on Saturday.
Spencer began the week as evens favourite to retain his Irish crown with Michael Kinane at 3-1 and Johnny Murtagh at 4-1.
But a flood of money led to Murtagh's odds being cut to 5-4 and Kinane's to 6-4 before Cashmans stopped taking bets.
Murtagh is now the favourite to take over from Spencer at Ballydoyle.