Disregard for an orderly open/close
This practice, better known as 'framing the opening' or ‘banging the close’, is when – either intentionally or recklessly – a market participant buys or sells large numbers of futures at the open/close to move the opening price or settlement price up or down.
This is usually done in order to benefit from an even larger position in an option, swap or other derivative that is cash-settled based on the futures settlement price.