In underwriting of shares, Unmarked application is totally opposite of marked application. In these applications, there is no any sign which shows the identity of any specific underwriter who has sold it. So, all these application's no. of shares are totalled by company and for reducing the liability of each underwriter, these total unmarked application shares are distributed among all the underwriters in their gross liability ratio and then deduct from gross liability of each underwriter. You can study the statement preparation for calculating the net liability of underwriter at here.