A joint tenant who sells their interest in a property does what in terms of that ownership?

When a joint tenant sells their interest in a property, they indeed transfer their ownership rights entirely to the buyer. This action results in a severance of the joint tenancy concerning that specific share of the property. The new owner who purchases the joint tenant's interest does not become a joint tenant with the remaining original joint tenants. Instead, they typically hold that interest as a tenant in common with the original joint tenants.

Joint tenancy requires the unities of time, title, interest, and possession, meaning all joint tenants must acquire their interest in the property simultaneously and under the same deed. Once one joint tenant sells their interest, that specific interest is no longer part of the joint tenancy arrangement, thus breaking the joint ownership. The remaining joint tenants still retain their interests, but the new owner’s participation in the ownership structure will be as a tenant in common, which fundamentally alters the nature of ownership.