Can a non-compete still follow a seller who only sold part of their shares?

Yes, a non-compete can still bind a seller who sold only part of their shares, as long as the covenant was validly given as part of that sale and its scope is reasonable. Ontario courts generally treat a non-competition covenant given by a seller in a business sale far more permissively than one imposed on an ordinary employee, because it is understood as protecting the goodwill the buyer actually paid for, not restraining someone's ability to earn a living. Selling less than 100% of the shares does not, by itself, take a seller outside that framework.

What matters more is the seller's ongoing role and what the covenant actually says. Employment Standards Act, 2000 restrictions on employee non-competes generally do not apply here unless the seller becomes an employee of the purchaser, at which point the business-sale exception under that Act typically preserves the covenant anyway. The covenant still needs to be reasonable in its scope, geography, and duration relative to the business interest being protected — there is no fixed length that makes a seller's non-compete automatically valid. A partial seller with an ongoing minority position should have the specific clause reviewed against these factors.