Circuit breakers for US Markets- NYSE

On October 1, 2008, the average value for the DJIA for the preceding month (September 2008) was used to calculate point levels (rounded to the nearest 50 points).
This resulted in the
Level One (10%) circuit breaker set at 1,100 points,
Level Two (20%) circuit breaker set at 2,200 points, and the
Level Three (30%) circuit breaker set at 3,350 points.

Information on SEC page

Pictorial representation on NYSE page:

http://www.nyse.com/press/circuit_breakers.html