<prompt> Human: Ok this might be a dumb question but Ive been contemplating it for the past month of so. Also the title may be confusing because I was having trouble wording it so lets look at an example:Vanguards SP 500 ETF VOO. According to their website 21.7 of all fund assets are in the largest 10 SP 500 companies. This means right? that every dollar invested in the fund will drive up the stock price of larger companies more so than the smaller ones. As more and more money moves into ETFs could we have an issue where this compounds in a way? The largest portion of every dollar invested in VOO is used to buy Apple. This drives up the stock price of Apple increasing Apples market cap. Over time this would mean a larger portion of funds assets are held in Apple. And as additional dollars are invested in VOO an even higher percentage of each dollar is invested in Apple.Is this something I should at all be concerned with? Is this working as expected. Im not trained in finance or anything so I expect I have some assumptionsconclusions wrong.  <response>: No. The fact is there are just way too many active investors out there. The number of hedge funds, family offices, traders, etc. in the market is huge and their trades are setting the prices for these ETFs. ETFindex money is just following where these traders set the price. Markets are not 100 efficient, but when youre talking about major publicly traded companies, there is just so much competition and analysis driving returns that active investors will find inefficiently priced stocks if ETFindex traders are propping up the prices of bad stock.I just dont buy it. Ive seen this raised a lot - but it mostly seems to come from people trying to push active investing. If there were a whole segment of companies overvalued based on money coming in from ETFs, the amount of money to be paid from shorting the overvalued losers would be astronomical and the inefficiency wouldnt last long. Having worked in the industry and seen the little edges HF investors look for, this would be like a gaping hole for investors 