[rprasad]

Founder stock is owned by the founder subject to repurchase right.

A repurchase right is a legally different concept from vesting. Repurchase rights only apply to vested stock.

Stock actually owned by a shareholder is vested stock. Stock only owned upon the occurrence of certain conditions which have not yet occurred is "unvested" stock. Unvested stock is not yet owned by the shareholder, and the shareholder has no legal, voting, or other rights arising from such stock. Hence, the company does not need to purchase it from the shareholder if the shareholder leaves before the unvested stock has vested. Thus, the article is incorrect as to what vested stock is.

It is possible to have stock vesting, acceleration, and repurchase rights associated with a single grant of stock. Each of these is a separate legal concept and each has different consequences.