IBB tracks an index of US biotechnology companies listed on the major US exchanges. This includes companies engaged in the research and development of therapeutic treatments but are not focused on the commercialization and mass production of pharmaceutical drugs. This also includes companies that are engaged in the production of tools or systems that enable biotechnology processes. IBB includes companies of all capitalizations, and weights using a modified market-cap methodology. Individual holdings are subject to capping requirements, 8% on the five largest constituents and 4% for the remaining. The index is rebalanced quarterly and fully reconstituted annually in December. Prior to June 21, 2021, the fund was named iShares Nasdaq Biotechnology ETF and tracked the NASDAQ Biotechnology Index.
