On July 2, the Investment Industry Regulatory Organization of Canada (IIROC) published a guidance note relating to securities trading halts in coordination with the application of 'circuit breakers' on U.S. markets. In the U.S., trading halts occur based on trigger levels of 10%, 20% and 30% drops of the Dow Jones Industrial Average, calculated at the beginning of each quarter using the previous month's average closing value. The NYSE thresholds have been announced for the third quarter of 2009 as 850 points, 1700 points and 2600 points respectively.

It is IIROC's policy that it will coordinate trading halts with U.S. markets, but for days when Canadian markets are open and American markets are closed, IIROC has published related triggers based on drops in the S&P/TSX Composite. The TSX trigger levels are: Level 1 (10%) - 1,050 points; Level 2 (20%) - 2,050 points and Level 3 (30%) - 3,100 points, with the effects of the triggers depending on the time of day the threshold drop occurs. Triggering the Level 1 threshold between 2:00 and 2:30 p.m. results in a 30 minute halt in trading, while trading would be shut down for the rest of the day should a Level 3 halt occur.