The legend of Black Caviar has translated into the highest price ever paid for a thoroughbred yearling at public auction in Australia with her half-brother making $5 million at the Easter Yearling Sale.

A huge crowd gathered when the colt by Redoute's Choice out of Helsinge entered the ring at the William Inglis sale yard in Sydney on Tuesday afternoon and they weren't disappointed.

Bidding began at $2 million with three groups entering the fray. At $3 million it was down to two with BC3 Thoroughbreds winning out over Swettenham Stud.

The syndication company also owns Black Caviar's half-sister, paying $2.6 million last year for the as yet unraced Belle Couture.

Bill Vlahos, the Australian chairman of BC3, admitted he was nervous, with the colt costing a bit more than they had wanted to pay.

"Our last bid was going to be $4.5 million so we were definitely over our limit," Vlahos said.

"We are excited to have him. We have 10 to 12 owners in the colt. There may be more shares available but Rick Jamieson has expressed an interest in buying in.

"We will talk to him first."

Vlahos said the colt would go to a Victorian trainer with Peter Moody and John Hawkes at the top of the list.

Moody is the trainer of champion Black Caviar and John Hawkes prepares her half-brother, star three-year-old All Too Hard who was a $1.025 million yearling.

William Inglis managing director Mark Webster said the colt had exceeded expectations.

"I was hoping he would beat the record," Webster said.

"I thought he might get to four (million) so he did exceed my expectations."

Webster said the international buying bench had been active, more than compensating for the absence of former big-spender Nathan Tinkler.

"We are not missing Nathan Tinkler because other buyers have come in and taken over," he said.

The beleaguered businessman withdrew his draft of 24 yearlings as he attempts to sell his Patinack Farm operation as a whole.

Webster said he did not expect the highs of Tuesday to be repeated on the second day.

"It could fall away tomorrow," he said.

"The average today was $305,000 and if it's $240,000 to $250,000 tomorrow that will still be up more than 10 per cent and I'll be happy.

"We sold four million-dollar-plus yearlings. It was the best trading day since the GFC in 2008."

Coolmore Stud and joint venture partner, the China Horse Club, bought the next highest priced yearlings, paying $2.4 million for a half-brother to dual hemisphere Group One winner Starspangledbanner and $1.5 million for a Fastnet Rock colt out of Dream Play.

The partnership between the dual hemisphere racing and breeding operation Coolmore and the China Horse Club was formed a year ago to promote horse racing in China.

They will hold a race meeting in Tianjin province in September but the expensive colts will remain in Australia for racing with about 60 tried horses going to China.