There is a private market for certain shares, and in most cases, the firm needs to give its permission before the shares can be sold. If they do, and there are

There is a private market for certain shares, and in most cases, the firm needs to give its permission before the shares can be sold. If they do, and there are eager purchasers on the market, then there won't be a problem. It is pointless if the corporation prevents every sale from occurring.