https://www.keeneland.com/media/news/fractional-interest-flightline-auction

the fine print:    Should Flightline continue to race beyond the Breeders’ Cup, the purchaser of the fractional interest will also be a part of his racing ownership.

I take all this to mean that shares are actually more for his breeding rights mostly, which would be a high dollar amount you'd need for a share like that (not like MyRacehorse kinda stufff) but if he DID continue racing  you'd be considered part ownership for the racing purses as well.   I can't imagine a share costing less than about $300K though??