Advertisements over a network, such as the Internet, by extracting an index file of suppliers of search result sets for a plurality of keywords and/or an index of ads to be placed. A keyword in a received query may be matched to the suppliers of related search result sets and/or the ads to be placed in the index file(s). The search results may be ranked based on various criteria such as yield, click through rates and history of dealings. Search result sets for the keywords from the matching suppliers and the ads to be placed may be combined to produce a search result set ranked in accordance with estimated yields for advertisements associated with each result in the search result set and delivered in response to the received query. The search results in the combined set may be reranked and/or repriced.