The goal of martingale is to be able to participate in bounces to the upside for quick flips, but also enter in lower if a position move against you. Right now is a great example of why we enter long. Just looking at the chart, it looks like it could keep going down to 400. But we don't know that.
What if it rebounds? We can start entering in small with the anticipating that if it goes down, we'll enter more for a rebound. (In this particular case, I have buys laddered down quite deep.) So if the market goes down to 350, I will be filled at 450 and 375 and my average cost will be around 425, roughly.
2 things happen as this occurring.
1. I can remain emotionally sane and not panic. I know that I have buys deeper than this if the market continues down.
2. My cost is averaging down.
Lets use this scenario that the market goes from where it is now to 350 as stated above. I had a 5% stop loss on a 100% portfolio entry point at 550. Now I have to enter again and risk another 5% at maybe 450. I could potentially get stopped out twice if the market is extremely volatile, maybe a 3rd? Person using the stop on a 10k portfolio if he were stopped out twice with a 5% risk factor is now at $9,025 looking to get back in to make it up. On a martingale strategy I would only be filled with 50% of the portfolio if it goes down to 350. Without doing the exact math, the loss would be higher, lets say a 10% stop loss, however a 10% loss on a 50% portfolio entry point at this juncture would still leave you with just losing $500, or twice as LESS risk then using stops.
Most importantly about the above scenario is the martingale allows you flexibility in times of market volatility and keeps you emotionally sane.
To summarize: Assess the risk of where a trade can go. Control your emotions and ladder your buys accordingly if you use this strategy. I hope this helps you better understand how I trade and helps you in your trading and money management. If it does support your trading, please send me love via my tweet on my twitter page.
Best,
-Sherem
A side note about massive Black Swann event's:
Of course if something happens like what happened with the swiss franc a few years back it's bad news bears all around. What you can do to really protect yourself in that event is put a stop loss behind your final martingale structure as discussed above.