Index funds account for only 1% of daily trading volume, with active traders, hedge funds, and individual investors making up the remaining 99%, suggesting they are not currently distorting the market.
"Vanguard did the research to find out how much of an impact index funds have on the market and the result was not much in fact they found that index funds only accounted for one percent of all daily trading volume and the other 99 was from active Traders hedge funds and individual investors meaning that no day-to-day Index Fund investing was not distorting the market"