Thursday, February 18, 2010

AUDJPY: Profit Is My Density

No, that's not a typo. It's a rip-off of a line from the Back To The Future movie. Anyway, this post is another in the series of theoretical considerations with respect to various robot building strategies.

In this scenario let's consider fixing our maximum total position size across a specific price range. For example, perhaps we are willing to purchase 10000 units per 1000 pips (remember, I'm generally talking about small account sizes). For Oanda traders this will run you up to about $175.00 in margin.

If you want to limit your overall positions to 10% of your account capital then you'll have to ante up $1750.00 to play in that 1000 pip range. Obviously, a large account value will either give you a larger playing field or a higher density of positions if you don't expand the playing field.

Are you still with me?

I know, at this point things are pretty boring. In fact, we're looking at a simple grid that we can play every time price passes through our space. However, this gets a bit spicier if we can find a way to optimize the open and close activities.

For example, what if we can compress our position openings towards the low end of a short term movement? Similarly, what if we can compress our position closings towards the higher end of price movements within our price space?

If you have good ideas for these processes, then you are set!

My thought is to adjust the probability of closing profitable positions based on the amount of profit a position embodies. For example, perhaps a position with a 10 pip profit has a 1% chance of being closed while a 20 pip profit has a 5% chance of being closed -- per bar. What would this do to the expected profit per position? Are some probability formulas able to provide much better returns?

Remember, we're talking about trading a maximum density of positions while prices move through our trading space. We know our total position, our total risk, and simply want to allow our winners to run as much as we can based on historical price movement patterns. Basically, we know that prices range for a while and then take off up or down. It's the multi-day upward movement that we want to catch... letting go of positions slowly during smaller moves until we can eventually latch onto a bigger move.

I'm probably about 85% into building a new robot based on this concept. I like the measured aspect of this on the risk side. I like the less definable profitability expectation -- it's beyond my math skills at any rate -- which is suggestive of an ability to preferentially capture larger profits. I also like that it should continue to eek out smaller profits if the price decides to languish in a smaller range for some period of time.

Maybe I'll be able to fire this up on Monday.

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