More typically, the company has the "right of first refusal" -- when a stockholder has an outside offer, they are first required to let the company buy their stock back at the price that the outsider is offering before selling to an outsider.
This is both to maintain control and to avoid having more than 500 shareholders, which triggers all kinds of additional regulations.
This is both to maintain control and to avoid having more than 500 shareholders, which triggers all kinds of additional regulations.