In its latest competitive bid to gain a larger portion of the online brokerage market, E-Trade (NasdaqGS: ETFC) will begin offering commission-free trading on 93 exchange traded funds.

According to E-Trade, clients will be allowed to buy and sell 93 ETFs from three fund sponsors: Deutsche Bank’s db-X, Global X and WisdomTree.

Potential investors should note that short sales, buy-to-cover and buy-write orders do not fall under commission-free trades. Options and options-exercise-related transactions are also not eligible. ETF trades will incur a small fee if the fund is sold within 30 days of purchase to discourage short-term trades.

It should be noted that while commission-free trades is a plus, long-term investors should look at a fund’s expense ratio when considering the total cost of the ETF investment.

The ETFs available for commission-free trades include both international and domestic equity offerings; a hand full of bond, currency and alternative ETFs; one Canada preferred stock ETF; and one foreign real estate ETF.

Chalres Schwab (NYSE: SCHW) offered commission-free trades on ETFs in 2009, and Fidelity Investments shortly followed. Last year, Vanguard started offering its clients free trades on its line of ETFs. More recently, Scottrade began offering tree trades on FocusShares ETFs. TD Ameritrade (NasdaqGS: AMTD) also allows commission-free trading on around 100 ETFs from various sponsors. [Brokers Offer Commission-Free ETF Trades]

For more information on ETFs, visit our ETF 101 category.

Max Chen contributed to this article.