If the articles provide that a class of shares is redeemable, at the corporation's discretion, then the corporation can require the shareholders of those redeemable shares to surrender the shares to the corporation in exchange for the redemption price set out in the articles. This price can be a fixed amount; fair market value at the time of redemption; or based on a formula as provided in the articles. If the corporation wishes to redeem fewer than all of the outstanding redeemable shares, this clause provides a mechanism for selecting whose shares will be redeemed, and gives the directors the authority to establish a system for choosing the shares to be redeemed by 'lot'. In theory this spreads the redemption fairly over the holders of the redeemable shares.