Understanding ETF costs.
Operating Expense Ratio (OER)	OERs are charged annually by the fund company, expressed as a percentage of a fund's average net assets. They cover the fund's management and other costs. Passively managed funds are designed to track a specific market index and typically have lower costs (OERs) than actively managed funds that pay fund managers or management teams to make ongoing decisions on where a fund's money is invested.
Trade Commission (online)	Your broker may charge you a trade commission each time you buy or sell an ETF.
Other Costs	Bid/Ask spreads and changes in discounts and premiums can also factor into your trade costs.