Reliability of the data for backtesting

Hi,
I just started the trial period with Portofolio123 so I am in testing phase. One of the test I have run was a screen with no rules. I expected performance at the benchmark level. However in the attached file you can see that with this screen on more than 6000 stocks I got annualized return over 1800% (with maximal one week return of 240%). Indeed this screen makes no practical sense but I am worried if I add some real rules the results will remain skewed.

Now the program is complaining so I cannot test it.
ERROR: Trial memberships are limited to a maximum number of 50 requests in a 6 hours period. Please try again later.

Any idea what is happening?

Best regards,

Martin


Portfolio123 - New Stock Screen.pdf (193 KB)

It’s the penny stocks causing those returns. Try adding rules to eliminate them, like

MktCap>100
Close(0) > 2

These rules will screen out stocks with Cap less than $100M and prices less than $2. Please note that the screener equally weights the stocks that pass, so the backtest will still do better than any benchmark which are typically cap-weighted.

We limit the number of requests during the free trial to avoid overloading the servers. We can end your trial manually by running the billing at your desired membership level, and you will be allowed up to 500 requests every 6 hours window. Let us know if you wish to do so.

Thanks

Hi Martin
Welcome to P123!

First of all, if you don’t use any rules you will get a whole bunch of penny stocks with very volatile price action. So use some price and liquidity rules to start.
(1) Close(0) >=3
(2) AvgDailyTot(60)>500000

The first rule filters out stocks trading below $3. The second rule filters out stocks with a 3 month Price x Volume daily average less than $500,000.

This would be a good place to start. You can adjust these figures to suit your taste once you get more familiar with P123.

The limit was imposed because there are too many smart programmers out there who get their computers to automatically run sims and download results over and over again. Once you have a full membership the limit increases to 500 accesses in a 6 hour period which is more reasonable. The small limit for trial memberships is because regular members keep signing up for trials using different email addresses to overcome the limits.

I think you will really enjoy P123. The community is very helpful so if you run into any problems don’t hesitate to post.

Steve

Thank you both. Makes complete sense, but still I am surprised by scope of the effect. I need to be more careful.
martin