市场变化有多大？ (How much has the market changed?)

Hello everyone,

Hopefully this is a quick question ;-)

I developed a strategy recently, and used Merlin's awesome "system behind the system" model (the thread is here: http://www.forexfactory.com/showthread.php?t=4446) for backtesting.

Everything looks great. I know why it works, the reasoning is sound (no martingale, hedging, gridding, insert your get-super-rich-or-blow-up-your-account-strategy here ;-) ), it's for a pair I'm very familiar with, and so far the forward test is going perfectly according to plan.

So, here's the question. I continued to backtest further and further back, and although it's still profitable, there are some VERY serious periods of drawdown in '03 and '99.

Is this something to be concerned about, or has the market simply changed in the last five years due to non-institutional traders entering the equation, or other factors?

If it has, why has it changed? Thoughts?

Thanks in advance for the input. FF ROX! :-)