system
A chat on subreddit /r/wallstreetbets
human
I don't see why. There is an arbitrage condition and I don't see how the tail would wag the dog. If a stock goes up 10% and makes up 10% of an ETF then the ETF should go up 1%.  Demand for an ETF creates demand for what it holds, true, but the APs will arb away any price discrepancies.

gpt
I agree with you.  Buts not my point.  My point is that if everyone is buying spy, the holdings themselves rise together generating price inefficiency, because not everything deserves the value incease.  Its why i believe there is a balance between active and passive managment.