ETF investors are becoming increasingly cost conscious. So in order to attract investors, ETF providers have also been aggressively cutting fees.Last month, Charles Schwab (SCHW) and Interactive Brokers (IBKR) announced they would offer zero commission trading on stocks & ETFs, which was followed by similar moves by TD Ameritrade (AMTD), Fidelity, E*Trade (ETFC) and Ally Invest.Investors should not let zero commissions dictate their trading behavior since there are other costs involved in trading.Five exchange traded products now have zero or negative fees. The Salt Low TruBeta US Market ETF (LSLT), SoFi Select 500 ETF (SFY) and SoFi Next 500 ETF (SFYX) have waived their fees for the first year, making them free to investors. The iPath Gold ETN (GBUG) and iPath Silver ETN (SBUG) are the first zero fee ETNs.While costs matter a lot, the difference becomes insignificant when it comes to a few basis points. And expense ratios are not the only factor that investors should consider while selecting ETFs. They should also look at trading costs and other implicit costs.Ultra-cheap, highly-liquid, broad market ETFs like the iShares Core S&P Total U.S. Stock Market ETF (ITOT) and Vanguard S&P 500 ETF (VOO) that charge just three basis points each, are as good as free ETFs. Top holdings in these ETFs include Microsoft (MSFT), Apple (AAPL) and Amazon (AMZN).To learn more, please watch the short video above.Want key ETF info delivered straight to your inbox?Zacks’ free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Amazon.com, Inc. (AMZN): Free Stock Analysis Report Apple Inc. (AAPL): Free Stock Analysis Report Microsoft Corporation (MSFT): Free Stock Analysis Report Vanguard S&P 500 ETF (VOO): ETF Research Reports iShares Core S&P Total U.S. Stock Market ETF (ITOT): ETF Research Reports SoFi Select 500 ETF (SFY): ETF Research Reports Salt Low truBeta US Market ETF (LSLT): ETF Research Reports SoFi Next 500 ETF (SFYX): ETF Research Reports iPath Silver ETN (SBUG): ETF Research Reports iPath Gold ETN (GBUG): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report