On Monday, the daughter of wonder mare Winx was sold for a record $10 million at the Inglis Australian Easter Yearling Sale at Warwick Farm, in Sydney.

Debbie Kepitis, a part-owner of Winx, fought off parties from around the world in a frenzied auction that opened at $2 million and went up mainly in $500,000 increases with each bid.

The daughter of late chicken king, racehorse owner and breeder Bob Ingham, was this month named on the Australian Rich Women List at No.50 with $320 million.

Overcome with emotion, Kepitis broke down after the auctioneer declared her the winning bidder.

Kepitis, whose family owns and runs the Woppitt Bloodstock operation, said she only decided in the past few weeks to buy the filly.

"(We thought) if we could get her we would," Kepitis said after completing the sale.

"I'm privileged to have been able to secure this filly on behalf of my family. To hopefully see if she can get to the racetrack, and if she can't, she will be an amazing mum. She's Australian forever, and she's going to be just fabulous."

After the sale, Tom Magnier from Coolmore Stud, which was the vendor, said it "feels like winning a Group 1".

"It's incredible," he said.

American thoroughbred tycoon John Stewart said in the lead up to the sale that he was prepared to pay $9 million for the leggy filly, which has racing royalty as her parents.

Instead the filly will stay in Australia and will almost certainly be trained by Chris Waller, who steered Winx to greatness.

Winx notched a world record 25 Group One victories world record 25 Group 1 races and was unbeaten in her last 33 race starts.

A winner of four Cox Plates, Winx captured the hearts and minds of race fans and drew worldwide attention.

The filly's sire, Pierro is a winner of the Triple Crown - Australia's three big races for two year olds.

When Winx retired to the Coolmore farm in 2019, her ownership group - Peter Tighe, Debbie Kepitis and the late Richard Treweeke - began matchmaking with Australia's prize stallions.

She lost a foal late into her pregnancy in 2020 and the Pierro filly is her first progeny to be sold.

A crowd of more than 5000 was at Warwick Farm on Monday to watch Lot 391 walk into the ring.

The yearling sold for a new Australian record, eclipsing the $5 million outlaid for a colt by Redoute's Choice at the 2013 Inglis Easter sales.

The most paid for a filly had been $2.6 million, which was for Belle Couture at last year's Magic Millions sale on the Gold Coast.

Inglis had inquiries about the Winx filly from potential buyers out of America, Japan and Europe as well as local thoroughbred investors.

Kepitis said it was a "very difficult decision" when announcing last September that the Winx foal would be sold rather than raced by the same ownership group.