HOLDRs differ from ETFs and mutual funds in several ways. First, the composition of a HOLDR is fixed and doesn't change over time, unless a company in the HOLDR goes bankrupt or is acquired. Second, HOLDRs are non-managed, meaning there's no professional fund manager making decisions about the HOLDR's composition. Lastly, holders of HOLDRs have beneficial ownership of the underlying stocks, not just units of the fund.