Didn't the "Turtles" of the 80's do the same thing based on ATR(9)?
Do the above rules apply across all boards? futures, currencies, stocks, options, etc?
The underlying component is that I examine trends and variations in the standard deviation of the security in order to get a sense as to "what happens if I'm wrong". Not sure if something like ATR(9) captures things because 9 periods is very small.
A good example:
If I'm trading earnings on company A, and have seen that std of 1-day chg is 5% and implied move is 8%, I'll know that I'll probably lose between that amount if I'm wrong on the day after earnings. I also find that PEAD persists for the next 30-days with average drawdown of -30%. The std of the quarter might be 15%, which tells me the variance I can expect in price.
Where do I set the stop limit? Early on, probably close to 15% and at earnings, somewhere around 5-6%.
Say I put the position on with a 15% stop loss. Two weeks later, a few companies down the value chain are experiencing weak sales. I take that to imply greater risk to my thesis (weaker sales down the chain, would impact new orders up the chain), revise my financial estimates, and trim the position. The stock moved down around 1%. Subsequently, the stock moves down with its peers -5% over the next few days.
A week after that, a peer company reports -- it beat street estimates but cut guidance, citing slowing growth and is down 6% overnight. My stock is down 4%. At this point, after reviewing my estimates and trimming my forecast, I now also expect the company to cut guidance and decide to sell out completely. I'm down on the trade by about 10%.
In real life, I'm usually paired against a peer that I expect will underperform, which dampens the volatility and usually results in a positive gain even if I'm wrong on the stock. If I held the stock through earnings and it "missed & lowered", I'd be forced to sell out of everything in the afterhours (assuming AMC release) and may go short depending on my view of the industry (perhaps at an inflection point that is turning solidly negative). "Stop losses" aren't too helpful in day-to-day risk or position management, but are there to set some type of normal limit to losses.