Does owning a minority stake in another company still make my corporation associated with it?

Yes, potentially. The associated corporation rules aren't limited to situations involving majority or controlling ownership, specific provisions can bring a corporation into associated status even where someone holds only a minority interest, particularly where deeming rules treat a group of related or connected shareholders as acting together, or where a significant minority interest combines with other factors to amount to control under the statutory tests.

This means owning what looks like a modest, non-controlling stake in another company doesn't automatically put you outside the associated corporation rules, and assuming a minority position is inherently safe from an association standpoint can be a real mistake. The specific ownership level that matters, and how it interacts with other shareholders' interests and relationships, depends on the particular deeming and control provisions that apply to your situation.

Because minority holdings can still trigger association in ways that aren't obvious just from looking at a stake on a cap table, anyone holding a minority interest in a corporation that might be connected to their other business interests should have the actual ownership structure reviewed against the associated corporation rules rather than assuming a lower ownership stake settles the question on its own.