Quote from john99:
I asked the same question to Dr. Steenbarger in his blog. He mentioned instituitions finishing trading and locals entering trading. I was thinking along the lines of overseas markets closing. I have to agree with brett that locals entering to trade would be a good reason. I'm not sure what technique pit traders use, but I'm guessing they use market profile to wait for the ideal setup to occur. They probably enter to trade when volume dries and the market reaches a low or high value which just happens to be around the 10:30am period.
If you look at volume during these key times you can see a pattern. But why is volume always highest the first hour and why do we see a decrease in volume around this period often followed by a reversal? When this pattern occurs I notice a higher probability of the market staying in a range for the day that reverses around high and low value areas based on the daily/weekly high volume S/R areas.
There is also another common occurence. If there is a HOD or LOD that is established during the 10:30am time period, the reversal tends to last for a 1 hour or a 2 hour period on the dot. Institutions exit trading, locals enter trading, and program trading kicks in. My guess is that many automated trading programs are set to close trades after a 1 or 2 hour period if no new low or high is made after the reversal period. If no new highs or lows are made then we normally revert back to the highest value area for the day. (taking into consideration that around 50% of the volume these days is made by trading programs this may be a logical hypothesis for this common occurence)
An example of this occurence from the last 2 days:
Tuesday reversal is at 10:40am, next reversal is at 12:40pm- 2 hours later on the dot, (note: 11:41 we broke lower, so the programs stayed short until 12:40pm)
Monday reversal 10:14am, next reversal is at 12:14 am. (note 11:15am we broke higher, so the buy programs stayed on until the 2 hour reversal)
I'm going to try to do more analysis of this pattern and post it in my blog. However blogger is down due to maintanence issues.