"Gambling syndicates are causing mayhem in horse racing by using algorithms to make huge, last-second bets that crush odds for regular players"

Dan Wolken for Yahoo:

Unlike sports wagering, where a bettor is playing against a bookmaker and locks in their odds at the time of the bet, American horse racing — which is in the spotlight this week for Saturday’s running of the 152nd Kentucky Derby — has long been based on a parimutuel system where the bettors are wagering against each other

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Thanks both to technology and the special privileges some racetracks have given them, the [Computer-Assisted Wagering syndicates] are able to upload tranches of bets directly into the wagering pool at lightning speeds — far faster than any regular player could do it on a phone app or at a racetrack window.

The ability to do it at the very last moment — sometimes significantly changing the odds for people who already made their bets — has become both the subject of a class-action federal lawsuit filed in the Eastern District of New York and a source of frustration for some high-profile voices in the sport who believe it has created too much inequity between the heavily capitalized professionals involved in CAWs and the common fan.