ETFs have a management fee built in. For example AGG Total Bond Market ETF has an expense ratio of 0.08%.
http://us.ishares.com/product_info/fund ... ew/AGG.htmWhether there is a brokerage commission for trading iShares ETFs is up to the brokerage firm.
-Fidelity has a deal where 30 iShares ETFs can be traded commission free.
https://www.fidelity.com/etfs/ishares-WellsTrade offers 100 free trades of almost anything in their PMA package.
-Vanguard Brokerage doesn't offer commission free trading for any iShares ETFs unless you get some free trades with Flagship status. Vanguard ETFs are commission free at Vanguard Brokerage.
Depending on where you invest, you should look at your mutual fund options and ETFs. An investor at Vanguard may find that it is easier to just use Vanguard mutual funds. An investor at Fidelity can compare Fidelity Spartan Index funds against iShares ETF. Wiki article link:
FidelityWiki article link:
ETFs vs Mutual Funds