What happens if a minority shareholder simply refuses to sign the closing documents?

It depends on what's actually being sold and how the transaction is structured. If the sale is of the corporation's assets rather than its shares, a properly passed special resolution authorizes the corporation itself to proceed, and an individual shareholder's signature on closing documents generally isn't required the way it would be for a personal share sale — a dissenting shareholder's refusal to sign doesn't usually stop an asset sale that's been properly authorized.

If instead individual shareholders are each selling their own shares, a holdout minority shareholder's refusal to sign can be a real obstacle unless the shareholders' agreement includes a drag-along provision compelling them to sell on the same terms as the majority. Where a shareholder is refusing to cooperate without a valid drag-along mechanism in place, the remaining path is usually negotiation, or in serious cases a court application — simply proceeding without their signature isn't an option if their individual shares are part of what's being sold.