The price change that occurs due to a sell or buy order. Broadly, it is the effect that results from a market participant buying or selling a security (or what is collectively known as an order book event) in a given market. Buying a security will drive its price up while selling it is expected to drive its price down, with everything else held constant.
The market impact is not always visible because the price usually keeps changing of its own accord. This impact may also vary, depending on the impact (s) already made or being made by other market participants at a given point in time.
In general, the market impact may, or may not, persist for long. Persistence of a market impact depends on many factors including size of new trades, and the market’s ability to absorb such trades, aggressiveness of price takers, etc.
