Market Wide Circuit Breakers (MWCB) will be implemented on April 8th, 2013 (date pending SEC approval). Under the current criteria, there would be a market halt of 30 minutes, should the Dow Jones Industrial Average change by approximately 1300 points. Under the new criteria, a 15 minute halt will be instituted should the S&P 500 change by more than 100 points (approximately). Here is the summary of changes to the MWCB from Colin Clark’s blog “Updating the Market-Wide Circuit Breaker” (see also the SEC Approval Order)
This summary is designed to give a basic overview of Limit Up/Limit Down and excludes many additional details including how LULD will work under various different trading situations. For a full explanation of LULD, please read the recommended links imbedded in the blog.
As of December 1, 2012.