Godolphin continued its spending on yearlings this year with the sale-topping Fastnet Rock filly at the Inglis Premier yearling sale on Tuesday.
The object of Godolphin desire was the second foal out of Group III Cockram Stakes winner Lady Melksham.
After opening at $100,000 it was Jason Walsh with the final bid at $500,000, outlasting trainer Brent Stanley.
Godolphin's racing and bloodstock manager said the filly exemplified what the blue operation was aiming to secure in 2018.
"What can I say, she's a quality filly by a champion sire out of a group winning mare," Walsh said.
"One of the things we are trying to source this year is a bit of diversity and top class racing prospects that will ultimately join our broodmare band and we thought this filly is capable of doing both those things."
Walsh said the September foal shapes in physique as a sprinter like her dam.
"She's sharp, very strong, a great attitude and off Rushton Park who are great supporters of ours," Walsh said.
"We are pleased to be supporting breeder's who have supported us.
"We're delighted to have secured her, that's our 16th yearling purchase this year so far - we got a lovely Shooting To Win yesterday and have been underbidder on a few here as we head into Easter."
