Subject: Re: Portfolio123 Testing 2026
*** 0. Limitations ***

1. Screening out IPOs in P123 is unclear. GTR1 does this with the field dspo. P123 can filter some IPOs with Close(253)>0, but this misses stocks that have pre-IPO prices.

2. Foreign stocks are defined differently, and so translating GTR1 styp.a=12 is unclear. Because of this, I usually start with the P123 ALLFUND Universe (that includes Foreign Primary and ADRs). ADRs and REITs can be filtered out if needed. Foreign stocks can't be filtered out the same in GTR1 and P123. The P123 field "Country of domicile" might work, but I did not test it.

3. P123 results sometimes change. The P123 database is not static, as changes are made to correct past mistakes. If you run the screens in this thread, GTR1 will always give the same CAGR, while P123 sometimes will give a different CAGR.

4. Different start dates give different P123 results. Just changing the start date by 1 day can change the P123 CAGR by more than 5% in a 10-year backtest.

5. I am mostly interested in monthly screens, long only, no hedging or timing, and no nano caps. So I did not do much testing on:
penny stocks (less than $1 Price)
nano caps (less than $50 million Market Cap)
daily or weekly trading
timing or hedging
ADR, MLP, ETF, or CEF
non-US stocks