BUSINESS
11/24/2008 05:12 am ET Updated May 25, 2011

When Does The Stock Market Freeze? US Stock Market Limits Rules

This morning, the US stock market futures were frozen after a maximum drop.

The current futures limits are as follows:

S&P 500 Futures: -60

Dow Jones Futures: -550

Nasdaq Futures: -85

They can drop no further until the market opens. These numbers are set quarterly, based on a 5% loss of the markets' values -- not current values, but the values when they were set. Then, these rules go into effect:

Limit extended to 10% at open.
Trading halted for 2 minutes if reached.

Limit then extended to 20%
Trading halted for 2 minutes if reached.

Limit then extended to 30%

Meanwhile, if the Dow were to drop 1100 points in trading today -- that would be the 10% marker that would freeze futures markets -- then these rules would go into effect:

If the Dow falls 1100 points before 2 p.m. we would see a one-hour trading halt.

If between 2-2:30 p.m., there is a 30-minute trading halt.

3 p.m. or later, there is no trading halt.

Source: CNBC

Oct. 27, 1997 was the last time there was a one-hour trading halt.