I've no idea if this edge thing is applicable since markets are not mechanical.
For example, how do you quantify a top Tennis/Soccer/Hockey player's edge? You could probably do it when faced up vs. another team/opponent, but what about a general edge?
... Actually, that doesn't sound dumb. Maybe your edge is something that only appears if the conditions are right, such as waiting for the right time to put on the trade.
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In any case, I stated in another thread that as a small player, your best edge is likely the ability to choose your battles and get in/out whenever you want. So while observing all the Big Boys pushing around price, you can wedge in at the right moment and make a profit.
That said, I "clicked" on trading a couple weeks ago when I made the relationship between trading and competition. I also presumed some predictability to prices. Thus I thought of two... axioms, I guess:
1) Trading is a competition.
2) Prices are relatively predictable.
If #2 holds true with #1, then what does a competitor do to make a predictable move, but still win? Why, he plays with your head, of course! So if you think of this, then you come up with a simple answer: competitors want you to close out your position (whether at a loss or profit is of no concern, both move price). They do this by shoving price in one direction or another before it finally goes where it was going all along. Risk management would be for those occasions where this isn't the case and price
really is trending the wrong way (i.e. against you).
So the idea is to "be with the money". You want to recognize situations in which the weak hands will pull out and push price in one direction, all according to how players perceive price movement.
And that, I think, is the edge any small player wants. It's the one I'm playing with, anyway.