Largest ETFs: Top 100 ETFs By Assets. The following table lists the top 100 largest exchange-traded funds, ranked by assets under management (AUM). The AUM of an ETF is calculated by multiplying shares outstanding by the market price per share. An ETFâs assets will fluctuate based on both changes in the value of the underlying securities and the creation of new shares or redemption of existing shares. It is worth noting that there may be a difference between an ETFâs market capitalization and the net asset value (NAV) of its underlying securities.