This position sizer generates wrong quantity in the alerts tab.

For example if I have set a "1% of equity" and "decrease size by 50%" then the alert quantity is equivalent to 1% of equity instead of being 0.5%.

However the trades are performed with the correct quantity providing a valid backtest result.

No, I don't think so. The alert size is being generated properly for me. Let's create a sample test case easy for me to reproduce (say, using "Moving Average Crossover" Strategy), and review your PosSizer settings.

To post an image of your PosSizer setup dialog, press Alt and Prt Scrn, then visit Snag.gy and simply paste it like the page instructs you to. Next, obtain the direct link by appending "i." to the URL as follows: "http://snag.gy/image.jpg" becomes "http://i.snag.gy/image.jpg" (without quotes). Finally, paste the direct link to the full-size image between a pair of IMG tags (you should see a pane with "...LINK, QUOTE, CODE, IMG" buttons when adding a new post).

In the first image you can see the alerts genarated in my strategy as of 1st of June 2012 along with the Position Sizer settings window. If you take for example the ABT buy alert the quantity is 1626 lots.

In the next image you can see that the alert generated to close the ABT fisrt trade is half that initial alert size (1626/2=813) which is the correct one. You can see here my point made in my first post that the trades done are correct but the alerts are still wrong.

I didn't create a sample case using a moving average crossover strategy cause I would have to search where is the point in time that the condition with the moving averages cross (in the equity curve) is met in order to reproduce the "error".

However if you believe that this is not enough evidence let me know to go through another example that you would be able to reproduce as well.

Thanks for your help

Thank you for the detailed report.

A debugging session shows that the EquityCurve and CashCurve values returned by Wealth-Lab to the PosSizer for sizing Alerts are the starting equity/cash values. This resets the sizing as if no historical equity curve was available at the moment. I'll find out whether this behavior is by design or not and post an update.

Thanks a lot Eugene

Please enter a support ticket to ensure that the issue won't get lost from our queue.

QUOTE:
A debugging session shows that the EquityCurve and CashCurve values returned by Wealth-Lab to the PosSizer for sizing Alerts are the starting equity/cash values.

I'd like to clarify and rephrase my conclusion: I've noticed that in Multi-Symbol backtests, the "EquityCurve" in PosSizers may deviate from the related "equity" value (which is correct). Since "Trading the Equity Curve" must rely on the EquityCurve series, it's made into thinking by the odd-looking EquityCurve series that the fast/slow MAs of equity haven't crossed, and applies the full position sizing (i.e. no size reduction). The issue is still under investigation.

This is now officially bug #68056.