A computer-implemented method of allocating to advertisers of marketable commodities on a digital advertising portal a share of marketing presence and/or marketing opportunities is disclosed. The commodities may be real estate properties. The method includes receiving from each advertiser one or more classified listings corresponding to marketable commodities, said classified listings including one or more commodity descriptors to allow for identification of said marketable commodities. A share of marketing presence and/or marketing opportunities on said digital advertising portal is then allocated to the advertisers, based upon at least said classified listings received from said advertiser. The share of marketing presence may be determined by calculating a listing value for each classified listing, based on a listing weighting associated with each classified listing. The classified listings may then be used to calculate respective advertiser values, on which the marketing share is based.