On April 5, 2011, the SEC announced that national securities exchanges and FINRA filed a proposal to establish a new "limit up-limit down" mechanism that would prevent trades in listed equity securities from occurring outside of a specified price band, which would be set at a percentage level above and below the average price of the security over the immediately preceding five-minute period. For stocks currently subject to the circuit breaker pilot, the percentage would be 5%, and for those not subject to the pilot, the percentage would be 10%. The percentage bands would be doubled during the opening and closing periods, and broader price bands would apply to stocks priced below $1.00. To accommodate more fundamental price moves, there would be a five-minute trading pause if trading is unable to occur within the price band for more than 15 seconds.

If approved by the SEC, the new limit up-limit down mechanism would replace the existing single stock circuit breakers, which were approved on a pilot basis. The exchanges and FINRA have requested that the SEC approve the plan as a one-year pilot program. The SEC will seek comment on the proposed plan, which is subject to Commission approval following a 21-day public comment period.

http://www.sec.gov/news/press/2011/2011-84.htm