ETFs can cost far less for an entry position—as little as the cost of one share, plus fees or commissions. An ETF is created or redeemed in large lots by institutional investors and the shares trade throughout the day between investors like a stock. Like a stock, ETFs can be sold short. 

Those provisions are important to traders and speculators, but of little interest to long-term investors. But because ETFs are priced continuously by the market, there is the potential for trading to take place at a price other than the true NAV, which may introduce the opportunity for arbitrage.

ETFs offer tax advantages to investors. As passively managed portfolios, ETFs (and index funds) tend to realize fewer capital gains than actively managed mutual funds.

Keynotes:

ETFs are more tax efficient than mutual funds because of the way they are created and redeemed.

For example, suppose an investor redeems $50,000 from a traditional Standard & Poor's 500 Index (S&P 500) fund. To pay the investor, the fund must sell $50,000 worth of stock. If appreciated stocks are sold to free up the cash for the investor, the fund captures that capital gain, which is distributed to shareholders before year-end. As a result, shareholders pay the taxes for the turnover within the fund. If an ETF shareholder wishes to redeem $50,000, the ETF doesn't sell any stock in the portfolio. Instead, it offers shareholders "in-kind redemptions," which limit the possibility of paying capital gains.