a large player can slice through bids, trapping the bidders, the advantage the large player has against numerous small players is instantaneous force. Whereas numerous small players have to be entrained into action over a period of time.
the average for every tic of slice is around 500 contracts, 500 x 4 x 10 = 20,000 contracts for every 10 points of slicing. A 30 point move in ES entails 30 = 60,000 contracts contracts, with no capital revitalization. How much margin is required for 60,000 contracts by the exchanges? 7088 per ES contract. 500 million, not much really if you look at the capital flows some of the large funds control, and not to mention some large families.
lets even double that number to 1000 per tic, so a billion. A billion dollars dumped into index futures can alter sentiment of a nation when its timed during news events irrespective of the actual news. Thats how the game is played.