A method for conducting an online group auction of homogeneous shares in an undivided lot uses a server computer accessible via a data network. An associated database contains details of an undivided lot, such as a real estate property, available for auction, and information representing a share offering. The offering comprises a number of homogeneous shares in the undivided lot, each share having an associate individual share price. Participating bidders submit bids via the data network, each bid including information identifying a maximum number of shares, and a maximum price per share. The server determines a degree of success of the bid based on an extent to which the maximum price per share exceeds a current individual share price of one or more of the homogeneous shares. The server then updates the information representing the share offering in accordance with the determined degree of success of the bid.