Waikato Stud has bought dual New Zealand Horse of the Year Bonneval and she will be served this season by I Am Invincible.

Bonneval's retirement was confirmed last week following her failure in her attempted defence of the Group One Underwood Stakes at Caulfield.

Mark Chittick of the famous New Zealand stud said they acted swiftly to secure Bonneval whose other wins include the NZ Oaks and Australian Oaks.

"She is on her way to Yarraman Park to be covered by I Am Invincible," Chittick said.

"She's a beautifully-bred mare and while one mare won't turn it around, it is a bit of a reversal of our top mares going overseas.

"It's a little bit of a turning of the tide and we're in this for the long haul."

A $150,000 yearling, Bonneval was trained by Murray Baker and Andrew Forsman.

She missed this year's autumn carnival because of a suspensory injury and was retired after two below-par runs this season.