Typically, the goal of a public offering is to price the security issue at the exact price at which all the issued shares can be sold to investors, so there will be neither a shortage nor a surplus of securities. When the pot is clean, the underwriter has no more of the issue to sell to interested investors. If there is still interest in the issue and nothing left for an underwriter to offer, it is probable that the issue was underpriced and oversubscribed.