the us market is quite amazing -, page-8

its not a free & open market........... circuit breakers that kick in if the market falls too far too quickly.

A 1050 point drop on the Dow before 2.00 pm EST will trigger a trading halt for one hour.

The same point drop will cause the market to shut for 30 minutes if it occurs between 2.00 pm and 2.30 pm.

If it occurs later than 2.30 the market will remain open.

A 2150 point drop in the Dow before 1.00 pm will halt trading for two hours.

The same sized drop will close the market for one hour if it occurs between 1.00 pm and 2.00 pm.

The market will shut for the remainder of the day if occurs after 2.00 pm.