Unknown hand

I am interested in the following question. How can you explain such a narrow SP range , volume of more than 800 thousand contracts,it's not so little, but is held for a long time during the trading session!?
How the range can be maintained with a variety of players with different objectives and strategies!!!
I can't believe in balance and equilibrium on supply and demand ( for all players) , for some reason, there is an unknown hand holding so narrowly and crumbling! …….