Wash trade

A wash trade is a form of market manipulation in which an investor simultaneously sells and buys the same financial instruments to create misleading, artificial activity in the marketplace. First, an investor will place a sell order, then place a buy order to buy from themself, or vice versa. This may be done for a number of reasons:
Some exchanges now have protections built in, sometimes mandatory for participants, such as STPF (Self-Trade Prevention Functionality) on the Intercontinental Exchange (ICE).
Wash trading has been illegal in the United States since the passage of the Commodity Exchange Act (CEA), of 1936.