RSS is the XML-based format for syndication of Web contents, and users aggregate RSS feeds with RSS feed aggregators. There are RSS aggregation policies that help aggregate RSS feeds effectively. In this paper, we first propose an aggregation policy to minimize the number of missing postings within an aggregation. Second, we analyze and compare our aggregation policy with existing aggregation policies. Our analysis reveals that our aggregation policy can reduce approximately 23% of the missing posts in comparison with an existing policy while it increases only 6% of the aggregation delay. Categories and Subject Descriptors H.3.3 [Information Storage and Retrieval]: Online Information Services ? data sharing, web-based services. General Terms Algorithms Keywords RSS, RSS Aggregator, Aggregation Policy