Bid-ask bounce
Technical analysisAlso called: Bid-offer bounce
Movement in a chart caused by consecutive trades printing on opposite sides of the spread rather than by any change in value.
In plain terms
Nobody transacts at the middle of the market, so a series of last traded prices zig-zags between the bid and the offer even on a day when nothing happens. It widens every bar by roughly one spread, and it manufactures apparent mean reversion in thin stocks.