The present invention primarily concerns hybrid auctions that may, for example, combine a clock auction with a proxy auction. Hybrid auctions include multi-item auctions that comprise at least two phases of package auctions: an earlier phase in which bidders participate in a clock auction (or other dynamic auction); and a later phase in which bidders participate in a proxy auction (or some other package auction). By combining the earlier phase and the later phase as in some of the embodiments described herein, it is possible to combine the advantages of the dynamic auction and the advantages of the sealed-bid package auction. In particular, if the earlier phase is a clock auction and the later phase is a proxy auction, then the resulting hybrid auction will combine the transparency and simplicity of the clock auction with the efficient outcome and competitive revenues of the proxy auction.