Well here is the Corn ETF:CORN line chart with the Sept Corn Futures chart overlaid in orange. They track close enough for trading. One doesn't have to be concerned with every tic like the futures contracts that can make or break you either as they trade just like a stock. A simple trailing stop loss well below price would work well in any uptrend. No limit moves in the ETFs either or other futures related issues. The ETFs wont track each and every contract anymore than each futures contract will. But overall it captures the true trend of the commodity and that is the point of them. Some use them as a hedge as well against a futures position. As far as liquidity goes they are all different. Some are fairly new and don't have a lot of volume yet. One would need to ask a broker about this on each. But they are growing exponentially in popularity and it wont be long before everything and every combination of things will be covered by an ETF of some sort.