What is the most expensive horse breed?

Thoroughbred Race Horses are the most valuable. A horses value is usually an estimation of it's earning potential as stud once it retires (this is where most of the money is made).The most valuable horse in the world is Frankel. Unbeaten in 13 starts, he's won every race in his two year career. His estimated value is a minimum of £100 million ($161 million).