ETNs are exchange-traded notes, an investment vehicle that gives investors the diversified benefits of both an exchange-traded fund (ETF) and a bond. ETNs are structured investments issued by a major bank or lender as senior debt notes. ETNs are similar to an ETF in that they both track an underlying index or asset class, such as commodities (energy, grains, livestock, industrial metals, petroleum), foreign currencies (yen, euro), and equities. Because ETNs are similar to bonds, they are subject to the financial strength of the backing institution. Investors like ETNs because they track an underlying index or equity exactly. ETNs are also not subject to annual taxes and can be deferred until it is sold or matures.