"Multi symbol backtest" and position size per trade
Author: RuneHS
Creation Date: 11/5/2009 5:32 PM
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RuneHS

#1
When doing "Multi Symbol Backtest", is it in any way possible to set the fixed dollar amount per single member/trade in the backtest?

Seems to me that the system calculates the "Quantity" (Q) via the "Entry price" (E), so that Q x E = position size (ref. the page/table "Trades"). That might work well for shares/equities. But if I want to include bond futures and foreign exchange (fx) crosses, there is perhaps a problem.

Let's take fx only as an even more simple example: If you have NOKUSD 6.11 (NOK per USD) then you'll get quantity 16.370 -> position size 100.000 - but that's 100.000 Norwegian krones. And if you have USDJPY (yen per USD) at 91.7 then you'll get Quantity 1.100 -> position size 100.000 - but that's 100.000 Japanese Yen this time. So the "base position size" is not denominated in the same currencies, and the positions are widely different in size.

Of course I could try to trick the in-data so that everything in effect is denomnated in the same currency (same value), but that will get very messy (fx crosses that are non-recognizable).

I believe that the only way put of this is to set the quantity per member of the "Multi Symbol Backtest". Is that possible in some way?
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Cone

#2
In 5.5, you can use the SetShareSize method in your script to logically size Positions. A more advanced method will be available in 5.6, PosSizers.
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RuneHS

#3
Sounds good, I am looking forward to the 5.6 version and the "PosSizers"!

An indicated, just to make things even clearer, the problem is really that WL cannot know what "6.11" is (in the example, it's number of NOK per USD). And then we might have fx crosses that does not involve USD at all, e.g. AUD vs. CAD or GBPJPY, making it hard to get the system to calculate the size of the position in terms of USD or some other base currency. If one could set the amount in each position manually, all would be right I figure. Apart from that, concerning fx and futures, the system works perfectly fine I think.

BTW when working with futures, a price of 101.14 or 121.79 is of course not the same thing as an equity/share, so the calculation of quantity become distorted regarding here, too.

So I am looking forward the the PosSizers. To have full flexibility I figure one should be able to get the amt. per "Multi Symbol member". Man, that would make WL a powerful portfolio simulation tool!

Kind regards, RuneHS
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Cone

#4
Sizing Position is one thing, but working with multi-currency instruments in the same backtest is another. It's not really possible, afaik.
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