The S & P index (and maybe all indexes) clearly recognizes certain price levels. The index may trade up to a price level that has acted as resistance before. The index usually pays attention to that price level by consolidating, rejecting or retracing to that level after passing through that price. The same thing happens on down movements. My point is that many of the moves on the S & P 500 are not random but auctions to various price levels. Hundreds of millions of shares that make up the index are traded each day and there is a huge volume of ETFâs and futures. Given the enormous volume, no one group can move the index. Small traders are meaningless in this process. Is it the independent decisions by big traders such as hedge funds, pension funds, brokerage companies, etc. all coming to the same trading decisions at the various price levels that moves the market? Are a majority of big players aware that say 1,380.50 has been resistance before and may be again. When the index gets close to that price does the majority close out their longs and other big players go short at that level? This may be a very basic question but I am trying to understand how a market with such huge volume moves as it does and who is responsible for the movement.