Groupon is a popular group-buying website offering daily deals and has experiencedfast growth. It has attracted amounts of imitators and they sprang up all over the world.We treat this phenomenon by taking Groupon as an intermediary executing coordinationbetween merchants and customers in the group-buying activities. To see the particularpractices of Groupon in operating transactional and relational coordination mechanisms,we collect diverse group-buying forms from the earliest buying club since 1860s tillnow and make comparison among various involved intermediaries. After that, five maindifferences are identified including the nature of initiator, product and service selection,pricing mechanism, frequency of deals, network and relations, which either contributesto reduction of transaction cost or maintaining the interactive relationships. Throughthese collection, comparison and analysis, we have new insights into the features ofGroupon’s group-buying coordination and accordingly implications for future electronicintermediaries.