Let me add by saying one of the most noticeable instances of this happening occured last year (late last year) on the stock Orica (ORI) - explosives maker, mining services etc etc...
The stock trades at ~$30 and was trading at around this level before a trader at obviously an inv bank or a hedge fund sold a large large large parcel at market.
He obviously knocked in a few too many zero's and didnt include a price level as the order sold the stock down from around (~) $30 to $9.
Someone here on HC said they bought some at around $10.
Immediately after the trade the stock kept trading at $30.
All trades on that order were cancelled by the offending brokers and the ASX settlements department.
Nothing will happen to your EPS trades or executed buy sell orders from yesterday
EPS Price at posting:
0.0¢ Sentiment: LT Buy Disclosure: Not Held