Hi traders, Can ETFs that track market indeces, such as SSO or FAS, etc., really purely track the corresponding index, irrespective of trading activity in the ETF itself? For example, say the Rifin is holding steady for a period of a few minutes, but during that time there is a great deal of buying interest in FAS, say half the average daily volume. I would think FAS would have to go up considerably, but it shouldn't if the Rifin is holding steady and FAS truly does track the performance of the Rifin. What gives? Can I buy a heck of a lot of FAS and expect to get a good fill as long the Rifin doesn't budge?