A share trader believed to have manipulated the market, has escaped with a formal warning from the Financial Markets Authority.

Spokeswoman Belinda Moffat says the trading occurred over a short period of time, provided no significant personal gain and was conducted on a online platform which did not offer guidance on prohibited activity.

She says the unnamed inexperienced trader engaged in "bait-and-switch" trading.

"It's where a trader places trades in the market to attract people into the market but doesn't complete those trades," she says.

"It creates an artificial or misleading appearance."