The NZX says shares accidently traded in Pike River Coal on Thursday are invalid and the price of the miner's stock, which was frozen at 88 cents two weeks ago, still stands.
Trading on share market was halted for two minutes on Thursday as a mark of respect for the 29 dead men.
But when it ended, trading in Pike River accidently resumed for a few seconds, causing the stock to plunge to 20c as automatic trades took effect.
NZX says that despite some market data showing otherwise, none of the trades are valid.
Twenty nine men are dead after a series of explosions at the mine since 19 November.