[gricardo99]

Just FYI, NYSE Rule 80B[1] halts trading for 15 minutes, or until the next day if the first 2 levels are breached. CME follows similar rules.

1 - http://wallstreet.cch.com/nyse/rules/nyse-rules/chp_1_3/chp_...

[greenyouse]

Just for fun here's a link to a 2010 flash crash before those rules were in place where a trillion dollars were dropped in half an hour due to algorithms.

https://en.wikipedia.org/wiki/2010_Flash_Crash