An abuse of power or authority over a market to prevent consumers from buying or using the product or service of a competitor. See conflict of interest and monopoly.
When MyCrudSoft first rolled out sWindles, they made sure that it produced an error message while installing onto a better version of DOS than their own, leading consumers to think the better DOS was flawed, even though sWindles worked with it just fine.
Kneejerk Corruptions, Incorrigible will do anything they can to prevent the owner of a domain from transferring it to another registrar. They did it best when they were also the register with which all the other registrars had to register domains.