When Forever Young and Voyage Bubble won Group 1 races on opposite sides of Asia within 15 hours in February, they became the latest members of one of horse racing's most exclusive groups - the US$10 million (HK$78 million) club.
In fact, after Forever Young became the 49th member with his Saudi Cup victory, Voyage Bubble quickly became the milestone 50th by taking the Hong Kong Gold Cup. That came almost 25 years after T M Opera O became the first horse to top US$10 million with his win in the 2000 Japan Cup.
It is a statistic brimming with numerous asterisks and caveats, given the global nature of racing and the many different ways such a metric can be calculated.
Ask America's Equibase, for instance, and there are 16 members of the club - and a 17th, the almighty Cigar, fell just US$185 short. However, their list is restricted to horses who had at least one start in the United States and there are issues with currency conversions too - particularly against the Japanese yen.
So how was this list determined?
Since the turn of the century, racing's global governing body - the International Federation of Horseracing Authorities - has issued an annual list of exchange rates with the US dollar, in conjunction with the International Grading and Race Planning Advisory Committee. It is usually based on the exchange rate at the start of each calendar year.
While a number of rich races either have a prize pool in American dollars or are run in countries whose currencies are pegged to the US dollar and do not fluctuate - think the Saudi riyal, the Emirati dirham or the Hong Kong dollar - a number of horses have competed in jurisdictions whose currencies can be wildly volatile against the US dollar. Chief among them are Britain's pound sterling, the euro, the Japanese yen and the Australian dollar.
By calculating a horse's annual earnings against those yearly exchange rates, the best measure of prizemoney in real terms can be made. It does not take inflation into account, merely how much a horse earned in American dollars at the time they raced.
The top two horses on the list would be clearly first and second, no matter how the totals are calculated: Hong Kong champions Romantic Warrior (US$28,595,253) and Golden Sixty (US$21,462,495). They are the only two members of the $20 million club.
Romantic Warrior, with US$28,595,253, tops the list of highest-earning racehorses of all time, no matter how the totals are calculated.
However, it is just behind them that a battle royale unfolds.
When legendary Australian mare Winx (US$19,049,695) retired in 2019, she was touted as the world's highest prizemoney earner. That was based on her Australian earnings at 2019 exchange rates but comparing others at 2019 exchange rates as well.
In real terms, though, that mantle was never hers. Both Gentildonna (US$19,691,454) and Orfevre (US$19,290,228) earned more on exchange rates as they were high performers at a time when the Japanese yen was at record highs. Comparatively, if a horse earned the same amount in yen today - when the currency is at record lows - they would struggle to crack the US$10 million barrier.
Ushba Tesoro (US$19,145,239), who was lucky to win most of his prizemoney away from Japan, just falls short of Gentildonna and Orfevre, although his sixth in the Dubai World Cup was enough for him to leapfrog Winx into fifth. By a quirk of currency conversion, he retired last week as Japan's highest-ever earner - a title which remains his when currency is converted into yen, even if he is not the highest Japanese horse on this list.
The top six are more than $1 million clear of numbers seven through 10: Equinox (US$17,760,228), Arrogate (US$17,422,600), Almond Eye (US$17,321,627) and T M Opera O (US$17,021,122).
Almost half of the 50 members of the club - 24 - are Japanese. Australia and the United States have seven members each, Hong Kong six, Great Britain four and Ireland and Saudi Arabia one apiece.
Andrew Hawkins, Idolhorse.com
