I have been day trading at a proprietary firm for years but only until recently I started looking at potential ETFs to day trade (a few weeks ago) and I have some questions... 1. How do ETFs go up or down in price on hardly any volume? Sometimes I notice that the holdings of the ETF are going up and the ETF is doing so as well on practically no buying. Is the market maker or market making algorithm just moving the bid and offer around depending on what the holdings are doing? 2. Can ETFs be "gamed"? For example a stock might be moving up simply because there is a big dark pool buyer or seller that needs to get in/out at that point in time. For ETFs, does this ever happen? From what I understand ETFs follow the holdings they are made up of. If someone tries to "block", say, the $5.10 price level of UNG while the natural gas stocks it represents are going up, won't arbitrageurs just keep buying UNG to put it in line with the holdings? I'm just trying to understand the world of ETFs and its mechanics better because I have been plenty of times massacred trying to play them like stocks short-term. It seems to me that it's a completely different playing field because they don't have a mind of their own: they follow the queues of their holdings. Am I wrong?